🌟 - 2023 DAY 13 SOLUTIONS -🌟

Day 13: Point of Incidence

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cacheson, 5 months ago

Nim

This one was a nice change of pace after the disaster of day 12. For part 1 I kept a list of valid column indexes, and checked those columns in each row for reflections, eliminating columns from the list as I went. To find vertical reflections, I just transposed the grid first.

Part 2 looked daunting at first, but I just needed to add a smudges counter to each column candidate, eliminating them when their counter reaches 2. For scoring, just count the 1-smudge columns.

Day 13, part 1

Day 13, part 2

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janAkali, 5 months ago (edited 5 months ago)

Nim

Part 1: For part 1 I just compare rows, then transpose matrix and compare rows again.
Part 2: For part 2 I compare rows and get symmetry type for each comparison: symmetric(==), almost symmetric (1 smudge), not symmetric (2+ difference). Then I just use two booleans to make sure we found exactly one smudge in each mirror.

Total runtime: 0.3 ms
Puzzle rating: 6/10
Code: day_13/solution.nim

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Deebster, 5 months ago

I decided to use string comparison for some reason, which meant part two wasn’t as quick as it would have been.


<span style="font-weight:bold;color:#a71d5d;">use </span><span style="color:#323232;">std::{cmp, fs, iter};
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">transpose</span><span style="color:#323232;">(rows: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;[</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">]) -> Vec {
</span><span style="color:#323232;">    (</span><span style="color:#0086b3;">0</span><span style="font-weight:bold;color:#a71d5d;">..</span><span style="color:#323232;">rows[</span><span style="color:#0086b3;">0</span><span style="color:#323232;">].</span><span style="color:#62a35c;">len</span><span style="color:#323232;">())
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|i| {
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> bytes: </span><span style="color:#0086b3;">Vec</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">lt;</span><span style="font-weight:bold;color:#a71d5d;">_> = </span><span style="color:#323232;">(</span><span style="color:#0086b3;">0</span><span style="font-weight:bold;color:#a71d5d;">..</span><span style="color:#323232;">rows.</span><span style="color:#62a35c;">len</span><span style="color:#323232;">()).</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|j| rows[j].</span><span style="color:#62a35c;">as_bytes</span><span style="color:#323232;">()[i]).</span><span style="color:#62a35c;">collect</span><span style="color:#323232;">();
</span><span style="color:#323232;">            </span><span style="color:#0086b3;">String</span><span style="color:#323232;">::from_utf8(bytes).</span><span style="color:#62a35c;">unwrap</span><span style="color:#323232;">()
</span><span style="color:#323232;">        })
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">collect</span><span style="color:#323232;">()
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">reflection_value</span><span style="color:#323232;">(rows: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;[</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">]) -> Option {
</span><span style="color:#323232;">    'row_loop: </span><span style="font-weight:bold;color:#a71d5d;">for</span><span style="color:#323232;"> i </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#0086b3;">0</span><span style="font-weight:bold;color:#a71d5d;">..</span><span style="color:#323232;">(rows.</span><span style="color:#62a35c;">len</span><span style="color:#323232;">() </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#0086b3;">1</span><span style="color:#323232;">) {
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">if</span><span style="color:#323232;"> rows[i] </span><span style="font-weight:bold;color:#a71d5d;">!=</span><span style="color:#323232;"> rows[i </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#0086b3;">1</span><span style="color:#323232;">] {
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">continue</span><span style="color:#323232;">;
</span><span style="color:#323232;">        }
</span><span style="color:#323232;">        </span><span style="font-style:italic;color:#969896;">// we have an initial match
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> other_matches </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">cmp::min(i, rows.</span><span style="color:#62a35c;">len</span><span style="color:#323232;">() </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#323232;"> i);
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">for</span><span style="color:#323232;"> j </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#0086b3;">1</span><span style="font-weight:bold;color:#a71d5d;">..=</span><span style="color:#323232;">other_matches {
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">if</span><span style="color:#323232;"> rows[i </span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#323232;"> j] </span><span style="font-weight:bold;color:#a71d5d;">!=</span><span style="color:#323232;"> rows[i </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#0086b3;">1 </span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;"> j] {
</span><span style="color:#323232;">                </span><span style="font-weight:bold;color:#a71d5d;">continue 'row_loop</span><span style="color:#323232;">;
</span><span style="color:#323232;">            }
</span><span style="color:#323232;">        }
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">Some</span><span style="color:#323232;">(i </span><span style="font-weight:bold;color:#a71d5d;">as u32 + </span><span style="color:#0086b3;">1</span><span style="color:#323232;">);
</span><span style="color:#323232;">    }
</span><span style="color:#323232;">    </span><span style="color:#0086b3;">None
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">summary</span><span style="color:#323232;">(file_path: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">) -> </span><span style="font-weight:bold;color:#a71d5d;">u32 </span><span style="color:#323232;">{
</span><span style="color:#323232;">    fs::read_to_string(file_path)
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">expect</span><span style="color:#323232;">(</span><span style="color:#183691;">"Can't read input file"</span><span style="color:#323232;">)
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">split</span><span style="color:#323232;">(</span><span style="color:#183691;">"</span><span style="color:#0086b3;">nn</span><span style="color:#183691;">"</span><span style="color:#323232;">)
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|s| {
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> rows: </span><span style="color:#0086b3;">Vec</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">lt;</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str> =</span><span style="color:#323232;"> s.</span><span style="color:#62a35c;">split</span><span style="color:#323232;">(</span><span style="color:#183691;">'</span><span style="color:#0086b3;">n</span><span style="color:#183691;">'</span><span style="color:#323232;">).</span><span style="color:#62a35c;">collect</span><span style="color:#323232;">();
</span><span style="color:#323232;">
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">if let </span><span style="color:#0086b3;">Some</span><span style="color:#323232;">(v) </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">reflection_value</span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;rows) {
</span><span style="color:#323232;">                v </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#0086b3;">100
</span><span style="color:#323232;">            } </span><span style="font-weight:bold;color:#a71d5d;">else </span><span style="color:#323232;">{
</span><span style="color:#323232;">                </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> cols_owned: </span><span style="color:#0086b3;">Vec </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">transpose</span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;rows);
</span><span style="color:#323232;">                </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> cols: </span><span style="color:#0086b3;">Vec</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">lt;</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str> =</span><span style="color:#323232;"> cols_owned.</span><span style="color:#62a35c;">iter</span><span style="color:#323232;">().</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|s| s.</span><span style="color:#62a35c;">as_str</span><span style="color:#323232;">()).</span><span style="color:#62a35c;">collect</span><span style="color:#323232;">();
</span><span style="color:#323232;">                </span><span style="color:#62a35c;">reflection_value</span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;cols).</span><span style="color:#62a35c;">expect</span><span style="color:#323232;">(</span><span style="color:#183691;">"No reflections found"</span><span style="color:#323232;">)
</span><span style="color:#323232;">            }
</span><span style="color:#323232;">        })
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">sum</span><span style="color:#323232;">()
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">str_diff</span><span style="color:#323232;">(str1: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">, str2: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">) -> </span><span style="font-weight:bold;color:#a71d5d;">u32 </span><span style="color:#323232;">{
</span><span style="color:#323232;">    iter::zip(str1.</span><span style="color:#62a35c;">chars</span><span style="color:#323232;">(), str2.</span><span style="color:#62a35c;">chars</span><span style="color:#323232;">())
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|(s1, s2)| </span><span style="font-weight:bold;color:#a71d5d;">if</span><span style="color:#323232;"> s1 </span><span style="font-weight:bold;color:#a71d5d;">==</span><span style="color:#323232;"> s2 { </span><span style="color:#0086b3;">0 </span><span style="color:#323232;">} </span><span style="font-weight:bold;color:#a71d5d;">else </span><span style="color:#323232;">{ </span><span style="color:#0086b3;">1 </span><span style="color:#323232;">})
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">sum</span><span style="color:#323232;">()
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">smudged_reflection_value</span><span style="color:#323232;">(rows: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;[</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">]) -> Option {
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">for</span><span style="color:#323232;"> i </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#0086b3;">0</span><span style="font-weight:bold;color:#a71d5d;">..</span><span style="color:#323232;">(rows.</span><span style="color:#62a35c;">len</span><span style="color:#323232;">() </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#0086b3;">1</span><span style="color:#323232;">) {
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> num_cmps </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">cmp::min(i, rows.</span><span style="color:#62a35c;">len</span><span style="color:#323232;">() </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#323232;"> i);
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> errs: </span><span style="font-weight:bold;color:#a71d5d;">u32 = </span><span style="color:#323232;">(</span><span style="color:#0086b3;">0</span><span style="font-weight:bold;color:#a71d5d;">..=</span><span style="color:#323232;">num_cmps)
</span><span style="color:#323232;">            .</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|j| </span><span style="color:#62a35c;">str_diff</span><span style="color:#323232;">(rows[i </span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#323232;"> j], rows[i </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#0086b3;">1 </span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;"> j]))
</span><span style="color:#323232;">            .</span><span style="color:#62a35c;">sum</span><span style="color:#323232;">();
</span><span style="color:#323232;">
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">if</span><span style="color:#323232;"> errs </span><span style="font-weight:bold;color:#a71d5d;">!= </span><span style="color:#0086b3;">1 </span><span style="color:#323232;">{
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">continue</span><span style="color:#323232;">;
</span><span style="color:#323232;">        }
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">Some</span><span style="color:#323232;">(i </span><span style="font-weight:bold;color:#a71d5d;">as u32 + </span><span style="color:#0086b3;">1</span><span style="color:#323232;">);
</span><span style="color:#323232;">    }
</span><span style="color:#323232;">    </span><span style="color:#0086b3;">None
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">smudged_summary</span><span style="color:#323232;">(file_path: </span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str</span><span style="color:#323232;">) -> </span><span style="font-weight:bold;color:#a71d5d;">u32 </span><span style="color:#323232;">{
</span><span style="color:#323232;">    fs::read_to_string(file_path)
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">expect</span><span style="color:#323232;">(</span><span style="color:#183691;">"Can't read input file"</span><span style="color:#323232;">)
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">split</span><span style="color:#323232;">(</span><span style="color:#183691;">"</span><span style="color:#0086b3;">nn</span><span style="color:#183691;">"</span><span style="color:#323232;">)
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|s| {
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> rows: </span><span style="color:#0086b3;">Vec</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">lt;</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str> =</span><span style="color:#323232;"> s.</span><span style="color:#62a35c;">split</span><span style="color:#323232;">(</span><span style="color:#183691;">'</span><span style="color:#0086b3;">n</span><span style="color:#183691;">'</span><span style="color:#323232;">).</span><span style="color:#62a35c;">collect</span><span style="color:#323232;">();
</span><span style="color:#323232;">
</span><span style="color:#323232;">            </span><span style="font-weight:bold;color:#a71d5d;">if let </span><span style="color:#0086b3;">Some</span><span style="color:#323232;">(v) </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">smudged_reflection_value</span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;rows) {
</span><span style="color:#323232;">                v </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#0086b3;">100
</span><span style="color:#323232;">            } </span><span style="font-weight:bold;color:#a71d5d;">else </span><span style="color:#323232;">{
</span><span style="color:#323232;">                </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> cols_owned: </span><span style="color:#0086b3;">Vec </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">transpose</span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;rows);
</span><span style="color:#323232;">                </span><span style="font-weight:bold;color:#a71d5d;">let</span><span style="color:#323232;"> cols: </span><span style="color:#0086b3;">Vec</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">lt;</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;</span><span style="font-weight:bold;color:#a71d5d;">str> =</span><span style="color:#323232;"> cols_owned.</span><span style="color:#62a35c;">iter</span><span style="color:#323232;">().</span><span style="color:#62a35c;">map</span><span style="color:#323232;">(|s| s.</span><span style="color:#62a35c;">as_str</span><span style="color:#323232;">()).</span><span style="color:#62a35c;">collect</span><span style="color:#323232;">();
</span><span style="color:#323232;">                </span><span style="color:#62a35c;">smudged_reflection_value</span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">&</span><span style="color:#323232;">amp;cols).</span><span style="color:#62a35c;">expect</span><span style="color:#323232;">(</span><span style="color:#183691;">"No reflections found"</span><span style="color:#323232;">)
</span><span style="color:#323232;">            }
</span><span style="color:#323232;">        })
</span><span style="color:#323232;">        .</span><span style="color:#62a35c;">sum</span><span style="color:#323232;">()
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">fn </span><span style="font-weight:bold;color:#795da3;">main</span><span style="color:#323232;">() {
</span><span style="color:#323232;">    println!(</span><span style="color:#183691;">" normal: </span><span style="color:#0086b3;">{}</span><span style="color:#183691;">"</span><span style="color:#323232;">, </span><span style="color:#62a35c;">summary</span><span style="color:#323232;">(</span><span style="color:#183691;">"d13/input.txt"</span><span style="color:#323232;">));
</span><span style="color:#323232;">    println!(</span><span style="color:#183691;">"smudged: </span><span style="color:#0086b3;">{}</span><span style="color:#183691;">"</span><span style="color:#323232;">, </span><span style="color:#62a35c;">smudged_summary</span><span style="color:#323232;">(</span><span style="color:#183691;">"d13/input.txt"</span><span style="color:#323232;">));
</span><span style="color:#323232;">}
</span>

Gobbel2000, 5 months ago

Rust

Part 2 turned out easier than I thought initially. My code assumes that there is only 1 mirror in each field which means I don’t have to remember where the smudge is, I just have to find a mirror line where the two halves differ at exactly one spot.

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mykl, 5 months ago

Dart

Just banging strings together again. Simple enough once I understood that the original reflection may also be valid after desmudging. I don’t know if we were supposed to do something clever for part two, but my part 1 was fast enough that I could just try every possible smudge location and part 2 still ran in 80ms


<span style="color:#323232;">bool reflectsH(int m, List p) => p.every((l) {
</span><span style="color:#323232;">      var l1 = l.take(m).toList().reversed.join('');
</span><span style="color:#323232;">      var l2 = l.skip(m);
</span><span style="color:#323232;">      var len = min(l1.length, l2.length);
</span><span style="color:#323232;">      return l1.take(len) == l2.take(len);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">bool reflectsV(int m, List p) {
</span><span style="color:#323232;">  var l1 = p.take(m).toList().reversed.toList();
</span><span style="color:#323232;">  var l2 = p.skip(m).toList();
</span><span style="color:#323232;">  var len = min(l1.length, l2.length);
</span><span style="color:#323232;">  return 0.to(len).every((ix) => l1[ix] == l2[ix]);
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="color:#323232;">int findReflection(List p, {int butNot = -1}) {
</span><span style="color:#323232;">  var mirrors = 1
</span><span style="color:#323232;">      .to(p.first.length)
</span><span style="color:#323232;">      .where((m) => reflectsH(m, p))
</span><span style="color:#323232;">      .toSet()
</span><span style="color:#323232;">      .difference({butNot});
</span><span style="color:#323232;">  if (mirrors.length == 1) return mirrors.first;
</span><span style="color:#323232;">
</span><span style="color:#323232;">  mirrors = 1
</span><span style="color:#323232;">      .to(p.length)
</span><span style="color:#323232;">      .where((m) => reflectsV(m, p))
</span><span style="color:#323232;">      .toSet()
</span><span style="color:#323232;">      .difference({butNot ~/ 100});
</span><span style="color:#323232;">  if (mirrors.length == 1) return 100 * mirrors.first;
</span><span style="color:#323232;">
</span><span style="color:#323232;">  return -1; //never
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="color:#323232;">int findSecondReflection(List p) {
</span><span style="color:#323232;">  var origMatch = findReflection(p);
</span><span style="color:#323232;">  for (var r in 0.to(p.length)) {
</span><span style="color:#323232;">    for (var c in 0.to(p.first.length)) {
</span><span style="color:#323232;">      var pp = p.toList();
</span><span style="color:#323232;">      var cells = pp[r].split('');
</span><span style="color:#323232;">      cells[c] = (cells[c] == '#') ? '.' : '#';
</span><span style="color:#323232;">      pp[r] = cells.join();
</span><span style="color:#323232;">      var newMatch = findReflection(pp, butNot: origMatch);
</span><span style="color:#323232;">      if (newMatch > -1) return newMatch;
</span><span style="color:#323232;">    }
</span><span style="color:#323232;">  }
</span><span style="color:#323232;">  return -1; // never
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="color:#323232;">Iterable> parse(List lines) => lines
</span><span style="color:#323232;">    .splitBefore((e) => e.isEmpty)
</span><span style="color:#323232;">    .map((e) => e.first.isEmpty ? e.skip(1).toList() : e);
</span><span style="color:#323232;">
</span><span style="color:#323232;">part1(lines) => parse(lines).map(findReflection).sum;
</span><span style="color:#323232;">
</span><span style="color:#323232;">part2(lines) => parse(lines).map(findSecondReflection).sum;
</span>

cvttsd2si, 5 months ago

Scala3


<span style="color:#323232;">// i is like
</span><span style="color:#323232;">//  # # # # #
</span><span style="color:#323232;">//   1 2 3 4
</span><span style="color:#323232;">def smudgesAround(i: Int, s: List[List[Char]]): Long =
</span><span style="color:#323232;">    val toEdge = math.min(i, s.size - i)
</span><span style="color:#323232;">    (0 until toEdge).map(e => s(i - e - 1).lazyZip(s(i + e)).count(_ != _)).sum
</span><span style="color:#323232;">
</span><span style="color:#323232;">def symmetries(g: List[List[Char]], smudges: Int) =
</span><span style="color:#323232;">    val rows = (1 until g.size).filter(smudgesAround(_, g) == smudges)
</span><span style="color:#323232;">    val g2 = g.transpose
</span><span style="color:#323232;">    val cols = (1 until g2.size).filter(smudgesAround(_, g2) == smudges)
</span><span style="color:#323232;">    100*rows.sum + cols.sum
</span><span style="color:#323232;">
</span><span style="color:#323232;">def task1(a: List[String]): Long = a.chunk(_ == "").map(g => symmetries(g.map(_.toList), 0)).sum
</span><span style="color:#323232;">def task2(a: List[String]): Long = a.chunk(_ == "").map(g => symmetries(g.map(_.toList), 1)).sum
</span><span style="color:#323232;">
</span>

to_urcite_ty_kokos, 5 months ago
Wouldn’t this code fail in a case like this? Because you count different lines, not different characters in the lines, right? Or am I missing something? Thanks (Let’s ignore column symmetry for the sake of example).
##
..
..
..

(I think you will get answer 100, but the answer is 300)

But for sure after seeing this I have to learn Scala.
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cvttsd2si, 5 months ago (edited 5 months ago)
On your example, my code produces 301, which matches your 300 ignoring column symmetry (and 0 for task2, as there is no way to smudge a single cell to create symmetry).

Let me explain the code real quick: What smudgesAround does is compute the number of tiles you would need to change to create a symmetry around index i. First, toEdge is the number of tiles to the nearest edge, everything after that will be reflected outside the grid and won’t matter. Then, for each actually relevant distance, we compare the rows/columns this distance from i. By zipping them, we create an Iterator that first yields the pair of first entries, then the pair of second entries, and so on. On each pair we apply a comparison, to count the number of entries which did not match. This is the number of smudges we need to fix to get these rows/columns to match. Summing over all relevant pairs of rows/columns, we get the total number of smudges to make i a mirror line. In symmetries, we just check each i, for task1 we want a mirror line without smudges and for task2 we want a mirror line for exactly one

You can also make this quite a bit shorter, if you want to sacrifice some more readability:
def compute(a: List[String], sm: Int) =
 a.chunk(_ == "").map(_.map(_.toList)).map(g => Seq(g, g.transpose).map(s => (1 until s.size).filter(i => (0 until math.min(i, s.size - i)).map(e => s(i - e - 1).zip(s(i + e)).count(_ != _)).sum == sm).sum).zip(Seq(100, 1)).map(_ * _).sum).sum

def task1(a: List[String]): Long = compute(a, 0)
def task2(a: List[String]): Long = compute(a, 1)

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to_urcite_ty_kokos, 5 months ago

Oh, I see, I for some reason switched zip operation with “create pair/tuple” operation in my head. Thanks for clarification.

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sjmulder, 5 months ago

C

Implementing part 1 with a bunch of for loops made me wonder about elegant NumPy solutions but then part 2 came along and it was a perfect fit! Just change a flag to a counter and remove the if-match-early-exit.

github.com/sjmulder/aoc/blob/master/…/day13.c


<span style="font-weight:bold;color:#a71d5d;">int </span><span style="font-weight:bold;color:#795da3;">main</span><span style="color:#323232;">()
</span><span style="color:#323232;">{
</span><span style="color:#323232;">	</span><span style="font-weight:bold;color:#a71d5d;">static char</span><span style="color:#323232;"> g[</span><span style="color:#0086b3;">32</span><span style="color:#323232;">][</span><span style="color:#0086b3;">32</span><span style="color:#323232;">];
</span><span style="color:#323232;">	</span><span style="font-weight:bold;color:#a71d5d;">int</span><span style="color:#323232;"> p1</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">,p2</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">, w,h, x,y,i, nmis;
</span><span style="color:#323232;">	
</span><span style="color:#323232;">	</span><span style="font-weight:bold;color:#a71d5d;">while </span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">!</span><span style="color:#62a35c;">feof</span><span style="color:#323232;">(stdin)) {
</span><span style="color:#323232;">		</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(h</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">; ; h</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">) {
</span><span style="color:#323232;">			</span><span style="color:#62a35c;">assert</span><span style="color:#323232;">(h </span><span style="font-weight:bold;color:#a71d5d;">< </span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">int</span><span style="color:#323232;">)LEN(</span><span style="font-weight:bold;color:#a71d5d;">*</span><span style="color:#323232;">g));
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">!</span><span style="color:#62a35c;">fgets</span><span style="color:#323232;">(g[h], LEN(</span><span style="font-weight:bold;color:#a71d5d;">*</span><span style="color:#323232;">g), stdin)) </span><span style="font-weight:bold;color:#a71d5d;">break</span><span style="color:#323232;">;
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">!</span><span style="color:#323232;">g[h][</span><span style="color:#0086b3;">0</span><span style="color:#323232;">] </span><span style="font-weight:bold;color:#a71d5d;">||</span><span style="color:#323232;"> g[h][</span><span style="color:#0086b3;">0</span><span style="color:#323232;">]</span><span style="font-weight:bold;color:#a71d5d;">==</span><span style="color:#183691;">'</span><span style="color:#0086b3;">n</span><span style="color:#183691;">'</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">break</span><span style="color:#323232;">;
</span><span style="color:#323232;">		}
</span><span style="color:#323232;">
</span><span style="color:#323232;">		</span><span style="color:#62a35c;">assert</span><span style="color:#323232;">(h</span><span style="font-weight:bold;color:#a71d5d;">></span><span style="color:#0086b3;">0</span><span style="color:#323232;">); w </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">strlen</span><span style="color:#323232;">(g[</span><span style="color:#0086b3;">0</span><span style="color:#323232;">])</span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#0086b3;">1</span><span style="color:#323232;">;
</span><span style="color:#323232;">		</span><span style="color:#62a35c;">assert</span><span style="color:#323232;">(w</span><span style="font-weight:bold;color:#a71d5d;">></span><span style="color:#0086b3;">0</span><span style="color:#323232;">);
</span><span style="color:#323232;">
</span><span style="color:#323232;">		</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(x</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">1</span><span style="color:#323232;">; x</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">w; x</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">) {
</span><span style="color:#323232;">			nmis </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0</span><span style="color:#323232;">;
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(i</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">; i</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">x </span><span style="font-weight:bold;color:#a71d5d;">&&</span><span style="color:#323232;"> x</span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;">i</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">w; i</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">)
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(y</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">; y</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">h; y</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">)
</span><span style="color:#323232;">				nmis </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> g[y][x</span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#323232;">i</span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#0086b3;">1</span><span style="color:#323232;">] </span><span style="font-weight:bold;color:#a71d5d;">!=</span><span style="color:#323232;"> g[y][x</span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;">i];
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(nmis</span><span style="font-weight:bold;color:#a71d5d;">==</span><span style="color:#0086b3;">0</span><span style="color:#323232;">) p1 </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> x; </span><span style="font-weight:bold;color:#a71d5d;">else
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(nmis</span><span style="font-weight:bold;color:#a71d5d;">==</span><span style="color:#0086b3;">1</span><span style="color:#323232;">) p2 </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> x;
</span><span style="color:#323232;">		}
</span><span style="color:#323232;">
</span><span style="color:#323232;">		</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(y</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">1</span><span style="color:#323232;">; y</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">h; y</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">) {
</span><span style="color:#323232;">			nmis </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0</span><span style="color:#323232;">;
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(i</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">; i</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">y </span><span style="font-weight:bold;color:#a71d5d;">&&</span><span style="color:#323232;"> y</span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;">i</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">h; i</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">)
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(x</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">0</span><span style="color:#323232;">; x</span><span style="font-weight:bold;color:#a71d5d;"><</span><span style="color:#323232;">w; x</span><span style="font-weight:bold;color:#a71d5d;">++</span><span style="color:#323232;">)
</span><span style="color:#323232;">				nmis </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> g[y</span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#323232;">i</span><span style="font-weight:bold;color:#a71d5d;">-</span><span style="color:#0086b3;">1</span><span style="color:#323232;">][x] </span><span style="font-weight:bold;color:#a71d5d;">!=</span><span style="color:#323232;"> g[y</span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;">i][x];
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(nmis</span><span style="font-weight:bold;color:#a71d5d;">==</span><span style="color:#0086b3;">0</span><span style="color:#323232;">) p1 </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> y</span><span style="font-weight:bold;color:#a71d5d;">*</span><span style="color:#0086b3;">100</span><span style="color:#323232;">; </span><span style="font-weight:bold;color:#a71d5d;">else
</span><span style="color:#323232;">			</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(nmis</span><span style="font-weight:bold;color:#a71d5d;">==</span><span style="color:#0086b3;">1</span><span style="color:#323232;">) p2 </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> y</span><span style="font-weight:bold;color:#a71d5d;">*</span><span style="color:#0086b3;">100</span><span style="color:#323232;">;
</span><span style="color:#323232;">		}
</span><span style="color:#323232;">	}
</span><span style="color:#323232;">
</span><span style="color:#323232;">	</span><span style="color:#62a35c;">printf</span><span style="color:#323232;">(</span><span style="color:#183691;">"13: </span><span style="color:#0086b3;">%d %dn</span><span style="color:#183691;">"</span><span style="color:#323232;">, p1, p2);
</span><span style="color:#323232;">	</span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">0</span><span style="color:#323232;">;
</span><span style="color:#323232;">}
</span>

hades, 5 months ago

Python

Also on Github


<span style="font-weight:bold;color:#a71d5d;">from .</span><span style="color:#323232;">solver </span><span style="font-weight:bold;color:#a71d5d;">import </span><span style="color:#323232;">Solver
</span><span style="color:#323232;">
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#323232;">is_mirrored_x</span><span style="color:#323232;">(pattern: </span><span style="color:#0086b3;">set</span><span style="color:#323232;">[</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]], max_x: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">, max_y: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">,
</span><span style="color:#323232;">                  x_mirror: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">, desired_errors: </span><span style="color:#0086b3;">int </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) -> </span><span style="color:#0086b3;">bool</span><span style="color:#323232;">:
</span><span style="color:#323232;">  min_x </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">max</span><span style="color:#323232;">(</span><span style="color:#0086b3;">0</span><span style="color:#323232;">, </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#323232;">x_mirror </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#323232;">max_x)
</span><span style="color:#323232;">  max_x </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">min</span><span style="color:#323232;">(max_x, </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#323232;">x_mirror)
</span><span style="color:#323232;">  errors </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">y </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">range</span><span style="color:#323232;">(max_y):
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">x </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">range</span><span style="color:#323232;">(min_x, x_mirror):
</span><span style="color:#323232;">      mirrored </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#323232;">x_mirror </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#323232;">x </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#0086b3;">1
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(x, y) </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#323232;">pattern </span><span style="font-weight:bold;color:#a71d5d;">and </span><span style="color:#323232;">(mirrored, y) </span><span style="font-weight:bold;color:#a71d5d;">not in </span><span style="color:#323232;">pattern:
</span><span style="color:#323232;">        errors </span><span style="font-weight:bold;color:#a71d5d;">+= </span><span style="color:#0086b3;">1
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(x, y) </span><span style="font-weight:bold;color:#a71d5d;">not in </span><span style="color:#323232;">pattern </span><span style="font-weight:bold;color:#a71d5d;">and </span><span style="color:#323232;">(mirrored, y) </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#323232;">pattern:
</span><span style="color:#323232;">        errors </span><span style="font-weight:bold;color:#a71d5d;">+= </span><span style="color:#0086b3;">1
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">errors </span><span style="font-weight:bold;color:#a71d5d;">> </span><span style="color:#323232;">desired_errors:
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">False
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#323232;">errors </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#323232;">desired_errors
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#323232;">is_mirrored_y</span><span style="color:#323232;">(pattern: </span><span style="color:#0086b3;">set</span><span style="color:#323232;">[</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]], max_x: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">, max_y: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">,
</span><span style="color:#323232;">                  y_mirror: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">, desired_errors: </span><span style="color:#0086b3;">int </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) -> </span><span style="color:#0086b3;">bool</span><span style="color:#323232;">:
</span><span style="color:#323232;">  min_y </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">max</span><span style="color:#323232;">(</span><span style="color:#0086b3;">0</span><span style="color:#323232;">, </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#323232;">y_mirror </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#323232;">max_y)
</span><span style="color:#323232;">  max_y </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">min</span><span style="color:#323232;">(max_y, </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#323232;">y_mirror)
</span><span style="color:#323232;">  errors </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">x </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">range</span><span style="color:#323232;">(max_x):
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">y </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">range</span><span style="color:#323232;">(min_y, y_mirror):
</span><span style="color:#323232;">      mirrored </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">2 </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#323232;">y_mirror </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#323232;">y </span><span style="font-weight:bold;color:#a71d5d;">- </span><span style="color:#0086b3;">1
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(x, y) </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#323232;">pattern </span><span style="font-weight:bold;color:#a71d5d;">and </span><span style="color:#323232;">(x, mirrored) </span><span style="font-weight:bold;color:#a71d5d;">not in </span><span style="color:#323232;">pattern:
</span><span style="color:#323232;">        errors </span><span style="font-weight:bold;color:#a71d5d;">+= </span><span style="color:#0086b3;">1
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(x, y) </span><span style="font-weight:bold;color:#a71d5d;">not in </span><span style="color:#323232;">pattern </span><span style="font-weight:bold;color:#a71d5d;">and </span><span style="color:#323232;">(x, mirrored) </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#323232;">pattern:
</span><span style="color:#323232;">        errors </span><span style="font-weight:bold;color:#a71d5d;">+= </span><span style="color:#0086b3;">1
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">errors </span><span style="font-weight:bold;color:#a71d5d;">> </span><span style="color:#323232;">desired_errors:
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">False
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#323232;">errors </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#323232;">desired_errors
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#323232;">find_mirror_axis</span><span style="color:#323232;">(pattern: </span><span style="color:#0086b3;">set</span><span style="color:#323232;">[</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]], max_x: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">, max_y: </span><span style="color:#0086b3;">int</span><span style="color:#323232;">,
</span><span style="color:#323232;">                     desired_errors: </span><span style="color:#0086b3;">int </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) -> </span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">None</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]</span><span style="font-weight:bold;color:#a71d5d;">|</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">None</span><span style="color:#323232;">]:
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">possible_x_mirror </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">range</span><span style="color:#323232;">(</span><span style="color:#0086b3;">1</span><span style="color:#323232;">, max_x):
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">is_mirrored_x(pattern, max_x, max_y, possible_x_mirror, desired_errors):
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#323232;">possible_x_mirror, </span><span style="color:#0086b3;">None
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">possible_y_mirror </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">range</span><span style="color:#323232;">(</span><span style="color:#0086b3;">1</span><span style="color:#323232;">, max_y):
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">is_mirrored_y(pattern, max_x, max_y, possible_y_mirror, desired_errors):
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">None</span><span style="color:#323232;">, possible_y_mirror
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">raise </span><span style="color:#0086b3;">RuntimeError</span><span style="color:#323232;">(</span><span style="color:#183691;">'No mirror axis found'</span><span style="color:#323232;">)
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">class </span><span style="color:#0086b3;">Day13</span><span style="color:#323232;">(</span><span style="color:#0086b3;">Solver</span><span style="color:#323232;">):
</span><span style="color:#323232;">
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#62a35c;">__init__</span><span style="color:#323232;">(self):
</span><span style="color:#323232;">    </span><span style="color:#62a35c;">super</span><span style="color:#323232;">().</span><span style="color:#62a35c;">__init__</span><span style="color:#323232;">(</span><span style="color:#0086b3;">13</span><span style="color:#323232;">)
</span><span style="color:#323232;">    self.patterns: </span><span style="color:#0086b3;">list</span><span style="color:#323232;">[</span><span style="color:#0086b3;">set</span><span style="color:#323232;">[</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]]] </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">[]
</span><span style="color:#323232;">    self.dimensions: </span><span style="color:#0086b3;">list</span><span style="color:#323232;">[</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]] </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">[]
</span><span style="color:#323232;">
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#323232;">presolve</span><span style="color:#323232;">(self, input: </span><span style="color:#0086b3;">str</span><span style="color:#323232;">):
</span><span style="color:#323232;">    patterns </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">input</span><span style="color:#323232;">.rstrip().split(</span><span style="color:#183691;">'</span><span style="color:#0086b3;">nn</span><span style="color:#183691;">'</span><span style="color:#323232;">)
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">pattern </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#323232;">patterns:
</span><span style="color:#323232;">      lines </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">pattern.splitlines()
</span><span style="color:#323232;">      points: </span><span style="color:#0086b3;">set</span><span style="color:#323232;">[</span><span style="color:#0086b3;">tuple</span><span style="color:#323232;">[</span><span style="color:#0086b3;">int</span><span style="color:#323232;">, </span><span style="color:#0086b3;">int</span><span style="color:#323232;">]] </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">set</span><span style="color:#323232;">()
</span><span style="color:#323232;">      max_x </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0
</span><span style="color:#323232;">      max_y </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0
</span><span style="color:#323232;">      </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">y, line </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">enumerate</span><span style="color:#323232;">(lines):
</span><span style="color:#323232;">        max_y </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">max</span><span style="color:#323232;">(max_y, y)
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">x, char </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">enumerate</span><span style="color:#323232;">(line):
</span><span style="color:#323232;">          max_x </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#62a35c;">max</span><span style="color:#323232;">(max_x, x)
</span><span style="color:#323232;">          </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">char </span><span style="font-weight:bold;color:#a71d5d;">== </span><span style="color:#183691;">'#'</span><span style="color:#323232;">:
</span><span style="color:#323232;">            points.add((x, y))
</span><span style="color:#323232;">      self.patterns.append(points)
</span><span style="color:#323232;">      self.dimensions.append((max_x </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#0086b3;">1</span><span style="color:#323232;">, max_y </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#0086b3;">1</span><span style="color:#323232;">))
</span><span style="color:#323232;">
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#323232;">solve_first_star</span><span style="color:#323232;">(self) -> </span><span style="color:#0086b3;">int</span><span style="color:#323232;">:
</span><span style="color:#323232;">    </span><span style="color:#62a35c;">sum </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">pattern, (max_x, max_y) </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">zip</span><span style="color:#323232;">(self.patterns, self.dimensions, strict</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">True</span><span style="color:#323232;">):
</span><span style="color:#323232;">      mirror_x, mirror_y </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">find_mirror_axis(pattern, max_x, max_y)
</span><span style="color:#323232;">      </span><span style="color:#62a35c;">sum </span><span style="font-weight:bold;color:#a71d5d;">+= </span><span style="color:#323232;">(mirror_x </span><span style="font-weight:bold;color:#a71d5d;">or </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#323232;">(mirror_y </span><span style="font-weight:bold;color:#a71d5d;">or </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#0086b3;">100
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#62a35c;">sum
</span><span style="color:#323232;">
</span><span style="color:#323232;">  </span><span style="font-weight:bold;color:#a71d5d;">def </span><span style="font-weight:bold;color:#323232;">solve_second_star</span><span style="color:#323232;">(self) -> </span><span style="color:#0086b3;">int</span><span style="color:#323232;">:
</span><span style="color:#323232;">    </span><span style="color:#62a35c;">sum </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#0086b3;">0
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">pattern, (max_x, max_y) </span><span style="font-weight:bold;color:#a71d5d;">in </span><span style="color:#62a35c;">zip</span><span style="color:#323232;">(self.patterns, self.dimensions, strict</span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#0086b3;">True</span><span style="color:#323232;">):
</span><span style="color:#323232;">      mirror_x, mirror_y </span><span style="font-weight:bold;color:#a71d5d;">= </span><span style="color:#323232;">find_mirror_axis(pattern, max_x, max_y, </span><span style="color:#0086b3;">1</span><span style="color:#323232;">)
</span><span style="color:#323232;">      </span><span style="color:#62a35c;">sum </span><span style="font-weight:bold;color:#a71d5d;">+= </span><span style="color:#323232;">(mirror_x </span><span style="font-weight:bold;color:#a71d5d;">or </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#323232;">(mirror_y </span><span style="font-weight:bold;color:#a71d5d;">or </span><span style="color:#0086b3;">0</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">* </span><span style="color:#0086b3;">100
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#62a35c;">sum
</span>

synae, 5 months ago

Here’s mine

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lwhjp, 5 months ago

Haskell

This was fun and (fairly) easy! Off-by-one errors are a likely source of bugs here.


<span style="color:#323232;">import Control.Monad
</span><span style="color:#323232;">import Data.List
</span><span style="color:#323232;">import Data.List.Split
</span><span style="color:#323232;">import Data.Maybe
</span><span style="color:#323232;">
</span><span style="color:#323232;">score d pat = ((100 *) <$> search pat) `mplus` search (transpose pat)
</span><span style="color:#323232;">  where
</span><span style="color:#323232;">    search pat' = find ((d ==) . rdiff pat') [1 .. length pat' - 1]
</span><span style="color:#323232;">    rdiff pat' i =
</span><span style="color:#323232;">      let (a, b) = splitAt i pat'
</span><span style="color:#323232;">       in length $ filter (uncurry (/=)) $ zip (concat $ reverse a) (concat b)
</span><span style="color:#323232;">
</span><span style="color:#323232;">main = do
</span><span style="color:#323232;">  input <- splitOn [""] . lines <$> readFile "input13"
</span><span style="color:#323232;">  let go d = print . sum . map (fromJust . score d) $ input
</span><span style="color:#323232;">  go 0
</span><span style="color:#323232;">  go 1
</span>

Line-seconds score: 0.102 😉

abclop99, 5 months ago

What does the line-seconds score mean?

Edit: lemmy.sdf.org/post/9116867

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lwhjp, 5 months ago (edited 5 months ago)

Yep, that’s it. (A totally scientific and non-fakeable measurement! /s)

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sjmulder, 5 months ago

Very pretty again!

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