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pvainiopvainio
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2022 day 12
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‎2022/go/day12/day12.go

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package main
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import (
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"fmt"
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"os"
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"strings"
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)
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func main() {
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input, _ := os.ReadFile("../../input/day12.txt")
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height, start, end := readMap(string(input))
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part1 := shortestPath(height, map[xy]int{}, visit{start, 0},
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func(dh int) bool { return dh <= 1 },
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func(p xy) bool { return end == p })
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part2 := shortestPath(height, map[xy]int{}, visit{end, 0},
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func(dh int) bool { return dh >= -1 },
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func(p xy) bool { return height[p] == 'a' })
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fmt.Printf("part1: %v\npart2: %v\n", part1, part2)
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}
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func shortestPath(height map[xy]int, visits map[xy]int, loc visit, ok func(d int) bool, target func(xy) bool) int {
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min := 9999
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if target(loc.xy) {
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return loc.distance
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} else if old, visited := visits[loc.xy]; visited && old <= loc.distance {
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return min
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}
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visits[loc.xy] = loc.distance
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for _, m := range []xy{{-1, 0}, {1, 0}, {0, -1}, {0, 1}} {
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next := visit{xy{loc.x + m.x, loc.y + m.y}, loc.distance + 1}
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if h, inside := height[next.xy]; inside {
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deltaH := h - height[loc.xy]
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if !ok(deltaH) {
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continue
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}
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d := shortestPath(height, visits, next, ok, target)
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if d < min {
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min = d
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}
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}
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}
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return min
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}
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func readMap(input string) (height map[xy]int, start, end xy) {
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rows := strings.Split(input, "\n")
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height = map[xy]int{}
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for y, row := range rows {
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for x, c := range row {
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if c == 'S' {
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start = xy{x, y}
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c = 'a'
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} else if c == 'E' {
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end = xy{x, y}
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c = 'z'
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}
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height[xy{x, y}] = int(c)
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}
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}
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return height, start, end
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}
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type visit struct {
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xy
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distance int
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}
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type xy struct {
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x, y int
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}

‎2022/input/day12.txt

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abaaaaaccccccccaaaaaaaaaaccccaaaaaaaaaccccaacccccccccccccccccccccaaaaaaaaaaaccaaaaaaaaaccccccccccaaaaaaaacaaaaaaccccccccccccccccccccccccccccccccccccccccccaaaaa
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abaaaaaaaccccccaaaaaaaaaacccccaaaaaacccccaaaacccccccccccccaacccccaaaaaaaaaaaacaaaaaaaaacccccccccaaaaaaaaaaaaaaaccccccccccccccccccccccccccccccccccccccccccccaaaa
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abacaaaaaccccccccaaaaaacccccccaaaaaacccccaaaacccccccccccccaacccaaaaaaaaaaaaaacaaaaaaaaccccccccccaaaaaaaaaaaaaaaaccccccccccccccccccccccccccaaaccccccccccccccaaaa
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abccaacccccccccccaaaaaaccccccaaaaaaacccccaaaacccaacccccaaaaaaaaaaaaaaaaaaaaacaaaaaaaccccccccccccacaaaaaccaaaaaaaccccccccccccccccccccccccccaaccccccccccccccaaaaa
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abcaaccccccccaaaaaaaaaaccccccaaacaaaccccccccccccaaaaaccaaaaaaaaaaaaaaaaaaaaaccaccaaacccccccccccccccaaaacccaaaaaaccccccccccccccccccccccccccaaacccccccccccccaaaca
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abcccccccccccaaaaaaaaaaaaacccccccccacccccccccccaaaaacccccaaaacaaaaaaaaaaaaccccaaaaaaccccccccaaacccccaaccccaacccccccccccccccccccccccaaaaccaaaccccccccccccccccccc
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abccccccccccaaaaaaccccaaaacccccccccccccccccccccaaaaaaccccaaaaaaaaaaaaaacaaacccaaaaaaaacccccaaaaaacccccccccccccccccccccccccccccccccccaaaaaaaaacccccccccccccccccc
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abacccccccccaaaaaacccccaaacaaacccccccccacccaaccccaaaacccaaacaaaaaaaaaaacccccccaaaaaaaacccccaaaaaaccccccccccccccccccccccccccccccccjjjjjjjaaaaaaaaaccccaacccccccc
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abaccccccccccaaaaaccaaaaaaaaaaccaccccccaacaaacccaaccccccaacccaaaaaaaaaaacccccccaaaaaaacccccaaaaaccccccccccccccccccccccccccccccccijjjjjjjjjhhhhhhhhhcaaaaaaccccc
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abaacccccccccaaaccccaaaaaaaaaaaaaccccccaaaaacccccccccccccccccccccaaaaaaacccccccaaaaaccccccccaaaaacccccccccccccccaaaaccccccccccciijjjjjjjjjhhhhhhhhhhcaaaaaccccc
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abaaccccccccccccccccccaaaaaacaaaaaacccccaaaaaacccccccccccaaacccccaaaccccccccccaaaaaaccccccccaacaacccccccccccccccaaaaccccccccccciiioooooojjhhhhpphhhhhaaaaaccccc
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abacccccccccccccccccccaaaaaaccaaaaacccaaaaaaaacccccccccccaaaaaaccaacccccccccccccccaaccccccccacccccccccccccccccccaaaaccccccccccciiioooooooooopppppphiiaaaaaacccc
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abaccccccccccaaaaaccccaaaaaaaaaaaaccccaaaaaaaacccccccccaaaaaaaaccccccccccccaaaaccccccccccccaaacccccccccccccccccccaaccccccccccciiinnoouuooooopppppppiiaaaaaacccc
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abcccccccccccaaaaaccccaaacaaaaccaacccccccaaccccccccccccaaaaaaaaccccccccccccaaaaccccccccaaacaaacccccccccccccccccccccccccccccccciiinnotuuuuoopuuuupppiiaaacaccccc
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abccccccccccaaaaaaccccaccccccccccccccccccaaccccccccccccaaaaaaacccccccaaacccaaaaccccccccaaaaaaaaaacccaacccccccccccccccccccccccciiinntttuuuuuuuuuuuppiiiaaccccccc
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abaaccccccccaaaaaaccccccccccccccccccaaaacccccccccccccccccaaaaaacccccaaaaccccaaccccccccccaaaaaaaaacccaaacaaacaaaccccccccccaaccciiinntttxxuuuuuuuuuppiiiccccccccc
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abaacccccccccaaaaaccccccccccccccccccaaaaccccccccaccccccccaaaaaacccccaaaaccccccccccccccccccaaaaacccccaaaaaaacaaaacccccccccaaaaiiiinnttxxxxuuyyyuvvppiiiccccccccc
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abaacccccccccaaaccccccccccccccccccccaaaaccaaacaaaacccccccaaccccccccccaaacccccccccccccccccaaaaaaccccccaaaaaacaaaacccccccccaaaaiiinnnttxxxxxxyyyvvppqiiiccccccccc
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abaccccccccccccccccccccaaccccccccccccaacccaaaaaaaacccccccccccccccccccccccccccccccccccaacaaaaaaacccaaaaaaaaccaaaccccccccaaaaahhhinnntttxxxxxyyyvvqqqiiiccccccccc
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abcccccccccccccccccccaaaaaaccccccccccccccccaaaaaaaaaccccccccccccccccccccccccccccccaaaaaaaaacaaacccaaaaaaaaaccccccccccccaaaaahhhnnnttttxxxxyyyvvvqqqiiiccccccccc
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SbcccccccccccccccccccaaaaaaccccccccccccccccaaaaaaaaaccccccccccccccccccccccccccccccaaaaacccccccacccaaaaaaaaaacccccccccccccaahhhnnntttxxxEzzzyyyvvvqqqjjjcccccccc
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abcccccccccccccccccccaaaaacccccccccccccaaaaaaaaaaaacccccccccccccccccccccccccccccccaaaaaaaccccccccccccaaacaaacccccccccccccahhhmmmtttxxxxxyyyyyyyvvvqqqjjjccccccc
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abccccccccccccccccccccaaaaacccccccccaacaaaaaaaaaaaaccccaccaaaccccccccccccccccccccaaaaaaaaccccccccccccaaacccccccccccccaaccahhhmmmtttxxxyywyyyyyyvvvqqqjjjccccccc
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abccccccccccccccccccccaaaaacccccccccaaaaaaaacaaacccccccaaaaaaccccaccaaaccccccccccaaaaaaaaccccccccccccaacccccccccccccaaaccchhhmmmsssxxwwwyyywyyvvvvqqqjjjccccccc
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abccaacccccccccccccccccccccccccccccccaaaaaaccaaacccccccaaaaaaccccaacaaacccccccccccacaaacccccccccccccccccccccccccaaaaaaaccchhhmmmssssswwwwyywwvvvvvqqqjjjdcccccc
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abccaaaccaaccccccccccccccccccccccccaaaaaaaaccaaccccccccaaaaaaacccaaaaaccccccccccccccaaacccccccccccccccccccccccccaaaaaaaaaahhhmmmmsssssswwywwwrvvqqqqqjjjdddcccc
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abccaaaaaaacccccaaaccccccccccccccccaaaaacaacccccccccccaaaaaaaaccccaaaaaaccccccccaaaccccccccccccccccccccccccccccccaaaaaaaaahhhgmmmmmsssswwwwwrrrrrqqqjjjjdddcccc
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abcccaaaaaacccccaaacacccccccccccccccccaaaccaacccccccccaaaaaaaaccaaaaaaaacaaccccaaaacccccccccccccccccccccccccccccccaaaaaaaccggggmmmmmmssswwwwrrrrrkjjjjjddddcccc
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abaaaaaaaaccccaacaaaaaccccaaacccccccccaaaccaaccccccccccccaaaccccaaaaacaaaaaccccaaaacccccccccccaacccccccccccaaccccaaaaaacccccgggggmmmllssswwrrrkkkkkjjjddddacccc
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abaaaaaaaaacccaaaaaaaaccccaaaacccccccccaaaaaaccccccccccccaaacccccccaacccaaacaaacaaaccccccccccaaaacccccccaaaaaacccaaaaaaacccccgggggglllsssrrrrrkkkkkkdddddaacccc
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abaaaaaaaaaacccaaaaaccccccaaaaccccccccccaaaaaaaccccccaaccccccccccccaaaaaaaaaaaaccccccccccccccaaaacccccccaaaaaccccaaccaaacccccccggggglllsrrrrrkkkeeedddddaaccccc
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abaacaaaaaaaccccaaaaacccccaaaccccccccccccaaaaaaccccaaaaccccccccccccccaaaaaaaaacccccccccccccccaaaacccccccaaaaaaacccccccaacccccccccgggglllrrrrkkkeeeeeddaaaaccccc
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abaaaaaacccccccaaacaacccccccccccccccccccaaaaaccccccaaaaaaccccccccaaacccaaaaacccccccccccccccccccccccccccaaaaaaaacccccccccccccccccccggfllllllkkkeeeeeccaaaaaacccc
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abaaaaacccccccccaacccccccccccccccccccccaaaaaacccccccaaaacccccacccaaccccaaaaaaccccccccccccccccccccccccccaaaaaaaacccccccccccaacccccccffflllllkkkeeeccccaaaaaacccc
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abaaaaacccccccccccccccccccccccccccaacccccccaaccccccaaaaacccccaaaaaaaccaaaaaaaaaaccccccccccccccccccccccccacaaacccccccccaaccaaccccccccfffllllkeeeecccccaacccccccc
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abaaaacccccccccccccccccccccccccccaaacccccccccccccccaacaacccccaaaaaaccaaaaacaaaaaccccccccccccccccccccccccccaaacccccccccaaaaaaccccccccffffffffeeeeccccccccccccccc
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abaaaccccccccccccccccccccccccccccaaaaacacccccccccccccccccccccaaaaaaaaaaaaccaaaaaaaaccccccaaccccccccccaaaaacccccccccccccaaaaaaacccccccfffffffeeaaccccccccccccaaa
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abaacccccaacaacccccccccccccaacaaaaaaaaaacccccccaaccccccccccccaaaaaaaaaaacccaaaaaaaacccccaaacaacccccccaaaaaccccccccccaaccaaaaaaccccccccafffffeaacccccccccccccaaa
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abaaaccccaaaaacccccccccccccaacaaaaaaaaaaccccccaaaccccccccccccaaaaaaaaaaaccccaaaaaccccccccaaaaaccccccaaaaaacccccccaacaaaaaaaaccccccccccaaacccccccccccccccccccaaa
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abccccccccaaaaacccccccccaaaaaaaaaaaaaacccccaaaaacaaccccccaaaaaaaaaaaaaaaaaaaaaaaaacccccaaaaaacccccccaaaaaacccccccaaaaaaaacaaccccccccccaaaccccccccccccccccaaaaaa
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abcccccccaaaaaacccccccccaaaaaaaaaaaaaacccccaaaaaaaaccccccaaaaacaaaaaaaaaaaaaaaaaaacccccaaaaaaaacccccaaaaaaccccccaaaaaaaaccaacccccccccccccccccccccccccccccaaaaaa

‎2022/java/Day12.java

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import java.nio.file.Files;
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import java.nio.file.Path;
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import java.util.HashMap;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Map;
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import java.util.function.Function;
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class Day12 {
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public static void main(String ... args) throws Exception {
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var map = readMap(Files.readString(Path.of("../input/day12.txt")));
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XY start = map.keySet().stream().filter(k -> map.get(k) == 'S').findFirst().get();
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XY end = map.keySet().stream().filter(k -> map.get(k) == 'E').findFirst().get();
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map.put(start, (byte) 'a');
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map.put(end, (byte) 'z');
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System.out.printf("part1: %d\n",
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shortestPath(map, new HashMap<>(), start, dh -> dh <= 1, p -> p.equals(end)));
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System.out.printf("part2: %d\n",
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shortestPath(map, new HashMap<>(), end, dh -> dh >= -1, p -> map.get(p) == 'a'));
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}
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static int shortestPath(Map<XY,Byte> map, Map<XY,Integer> visits, XY start,
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Function<Byte,Boolean> ok, Function<XY,Boolean> target) {
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var visited = new HashMap<XY,Integer>();
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var toVisit = new LinkedList<Visit>();
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toVisit.add(new Visit(start, 0));
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while(!toVisit.isEmpty()) {
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var c = toVisit.removeFirst();
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if (!visited.containsKey(c.xy) || visited.get(c.xy) > c.distance) { // not visited or longer distance
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visited.put(c.xy, c.distance); // visit
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moves.stream().map(m -> c.move(m)) // next location
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.filter(n -> map.containsKey(n.xy)) // is inside map
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.filter(n -> ok.apply((byte) (map.get(n.xy) - map.get(c.xy)))) // ok to climb
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.forEach(n -> toVisit.add(n)); // add to visit list
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}
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}
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return visited.keySet().stream()
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.filter(p -> target.apply(p)) // match or target
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.map(p -> visited.get(p)) // map to distance
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.sorted().findFirst().get(); // get minimum
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}
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static Map<XY,Byte> readMap(String input) {
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Map<XY,Byte> map = new HashMap<>();
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var lines = input.lines().toList();
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for (int y = 0; y < lines.size(); y++) {
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for (int x = 0; x < lines.get(y).length(); x++) {
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map.put(new XY(x,y), (byte) lines.get(y).charAt(x));
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}
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}
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return map;
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}
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record Visit(XY xy, int distance) {
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Visit move(XY v) { return new Visit(new XY(xy.x+v.x, xy.y+v.y), distance + 1); }
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}
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record XY(int x, int y) {}
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static List<XY> moves = List.of(new XY(1,0), new XY(-1,0), new XY(0,1), new XY(0,-1));
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}

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