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| 1 | +package com.codefork.aoc2024.day25; |
| 2 | + |
| 3 | +import com.codefork.aoc2024.Problem; |
| 4 | +import com.codefork.aoc2024.util.Assert; |
| 5 | +import com.codefork.aoc2024.util.Grid; |
| 6 | +import com.codefork.aoc2024.util.WithIndex; |
| 7 | + |
| 8 | +import java.util.ArrayList; |
| 9 | +import java.util.HashSet; |
| 10 | +import java.util.List; |
| 11 | +import java.util.Set; |
| 12 | +import java.util.stream.IntStream; |
| 13 | +import java.util.stream.Stream; |
| 14 | + |
| 15 | +public class Part01 extends Problem { |
| 16 | + |
| 17 | + public record Position(int x, int y) { |
| 18 | + |
| 19 | + } |
| 20 | + |
| 21 | + public record Schematic(Set<Position> positions) { |
| 22 | + |
| 23 | + public List<Integer> getHeights() { |
| 24 | + return IntStream.range(0, 5) |
| 25 | + .boxed() |
| 26 | + .map(x -> (int) positions().stream().filter(p -> p.x() == x).count()) |
| 27 | + .toList(); |
| 28 | + } |
| 29 | + |
| 30 | + } |
| 31 | + |
| 32 | + record LockAndKey(Schematic lock, Schematic key) { |
| 33 | + |
| 34 | + } |
| 35 | + |
| 36 | + public String solve(Stream<String> data) { |
| 37 | + var schematics = Grid.parse(data, |
| 38 | + () -> new ArrayList<Schematic>(), |
| 39 | + (acc, x, y, ch) -> { |
| 40 | + y = y % 8; |
| 41 | + if(x == 0 && y == 0) { |
| 42 | + acc.add(new Schematic(new HashSet<>())); |
| 43 | + } |
| 44 | + var schematic = acc.getLast(); |
| 45 | + if("#".equals(ch)) { |
| 46 | + schematic.positions().add(new Position(x, y)); |
| 47 | + } |
| 48 | + return acc; |
| 49 | + }); |
| 50 | + |
| 51 | + var keys = schematics.stream() |
| 52 | + .filter(s -> |
| 53 | + s.positions().stream().anyMatch(p -> p.y() == 6) |
| 54 | + ) |
| 55 | + .toList(); |
| 56 | + |
| 57 | + var locks = schematics.stream() |
| 58 | + .filter(s -> |
| 59 | + s.positions().stream().anyMatch(p -> p.y() == 0) |
| 60 | + ) |
| 61 | + .toList(); |
| 62 | + |
| 63 | + // note that we calculate height differently than in the problem description |
| 64 | + |
| 65 | + // all valid lock and key combos |
| 66 | + var combos = locks.stream() |
| 67 | + .flatMap(lock -> { |
| 68 | + var lockHeights = lock.getHeights(); |
| 69 | + return keys.stream() |
| 70 | + .filter(key -> { |
| 71 | + var keyHeights = key.getHeights(); |
| 72 | + return keyHeights.stream() |
| 73 | + .map(WithIndex.indexed()) |
| 74 | + .noneMatch(heightWithIdx -> { |
| 75 | + var i = heightWithIdx.index(); |
| 76 | + var height = heightWithIdx.value(); |
| 77 | + return lockHeights.get(i) + height > 7; |
| 78 | + }); |
| 79 | + }) |
| 80 | + .map(key -> new LockAndKey(lock, key)); |
| 81 | + }) |
| 82 | + .toList(); |
| 83 | + |
| 84 | + return String.valueOf(combos.size()); |
| 85 | + } |
| 86 | + |
| 87 | + @Override |
| 88 | + public String solve() { |
| 89 | + Assert.assertEquals("3", solve(getSampleInput())); |
| 90 | + return solve(getInput()); |
| 91 | + } |
| 92 | + |
| 93 | + public static void main(String[] args) { |
| 94 | + new Part01().run(); |
| 95 | + } |
| 96 | + |
| 97 | +} |
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