Aoc24.12

gistfile1.txt

package yk.aoc2024;

import org.junit.Test;
import yk.aoc2024.utils.AocUtils2D;
import yk.jcommon.fastgeom.Vec2i;
import yk.jcommon.fastgeom.yfor.YForVec2i;
import yk.ycollections.Tuple;
import yk.ycollections.YList;
import yk.ycollections.YSet;

import static org.junit.Assert.assertEquals;
import static yk.aoc2024.utils.AocUtils.INT_ADD;
import static yk.aoc2024.utils.AocUtils.readPuzzle;
import static yk.aoc2024.utils.AocUtils2D.*;
import static yk.jcommon.fastgeom.Vec2i.v2i;
import static yk.ycollections.YArrayList.al;
import static yk.ycollections.YHashSet.hs;
import static yk.yfor.YForGen.yfor;
import static yk.yfor.YForGenerators.yfor;

public class Aoc12 {

    public static String TEST_INPUT_1 =
        "AAAA\n" +
        "BBCD\n" +
        "BBCC\n" +
        "EEEC";

    public static String TEST_INPUT_2 =
        "OOOOO\n" +
        "OXOXO\n" +
        "OOOOO\n" +
        "OXOXO\n" +
        "OOOOO";

    public static String TEST_INPUT_21 =
        "EEEEE\n" +
        "EXXXX\n" +
        "EEEEE\n" +
        "EXXXX\n" +
        "EEEEE";

    public static String TEST_INPUT_22 =
        "AAAAAA\n" +
        "AAABBA\n" +
        "AAABBA\n" +
        "ABBAAA\n" +
        "ABBAAA\n" +
        "AAAAAA";

    public static String TEST_INPUT_3 =
        "RRRRIICCFF\n" +
        "RRRRIICCCF\n" +
        "VVRRRCCFFF\n" +
        "VVRCCCJFFF\n" +
        "VVVVCJJCFE\n" +
        "VVIVCCJJEE\n" +
        "VVIIICJJEE\n" +
        "MIIIIIJJEE\n" +
        "MIIISIJEEE\n" +
        "MMMISSJEEE";

    @Test
    public void test1() {
        assertEquals(140, solve1(TEST_INPUT_1));
        assertEquals(772, solve1(TEST_INPUT_2));
        assertEquals(1930, solve1(TEST_INPUT_3));
    }

    @Test
    public void test2() {
        assertEquals(80, solve2(TEST_INPUT_1));
        assertEquals(436, solve2(TEST_INPUT_2));
        assertEquals(236, solve2(TEST_INPUT_21));
        assertEquals(368, solve2(TEST_INPUT_22));
        assertEquals(1206, solve2(TEST_INPUT_3));
    }

    @Test
    public void solution1() {
        assertEquals(1461806, solve1(readPuzzle("aoc12.txt")));
    }

    @Test
    public void solution2() {
        assertEquals(887932, solve2(readPuzzle("aoc12.txt")));
    }

    private int solve1(String input) {
        return extractFields(parse2d(input))
            .map(f -> f.size() * f.reduce(0, (i, pos) -> i + DIRS.filter(d -> !f.contains(d.add(pos))).size()))
            .reduce(INT_ADD);
    }

    private int solve2(String input) {
        YSet<Tuple<Vec2i, Vec2i>> seen = hs();
        return extractFields(parse2d(input)).map(field -> yfor(field)
            .flatMap(pos -> DIRS
                .filter(dir -> !field.contains(pos.add(dir)))
                .filter(dir -> !seen.contains(new Tuple<>(pos, dir)))
                .map(dir -> al(dir.rot90(), dir.rot_90()).map(d -> yfor(pos, p -> p.add(d))
                    .whilst(p -> field.contains(p) && !field.contains(p.add(dir)))
                    .peek(p -> seen.add(new Tuple<>(p, dir)))
                    .count())))
            .count() * field.size()).reduce(INT_ADD);
    }

    private static YList<YSet<Vec2i>> extractFields(YList<YList<String>> map) {
        YSet<Vec2i> seen = hs();
        return new YForVec2i(v2i(0), v2i(map.first().size(), map.size()))
            .filter(p -> !seen.contains(p))
            .map(p -> {
                YSet<Vec2i> fieldBody = hs(p);
                String fieldType = getAt(map, p);

                YSet<Vec2i> edge = hs(p);
                while (edge.notEmpty()) {
                    edge = edge.flatMap(e -> AocUtils2D.DIRS
                        .map(d -> e.add(d))
                        .filter(p2 -> !fieldBody.contains(p2))
                        .filter(p2 -> fieldType.equals(getAtOr(map, p2, null)))
                        .forThis(m -> fieldBody.addAll(m)));
                }
                seen.addAll(fieldBody);
                return fieldBody;
            }).toList();
    }
}