Day 18

2024/18/index2.ts

@@ -0,0 +1,163 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8').split("\n");
+
+interface Coord {
+    x: number,
+    y: number,
+};
+
+enum Dir {
+    Up,
+    Right,
+    Down,
+    Left,
+};
+
+const map: Array<Array<string|number>> = [];
+
+const width = 71;
+const height = 71;
+
+for (let y = 0; y < height; y++) {
+    if (!map[y]) {
+        map[y] = [];
+    }
+    for (let x = 0; x < width; x++) {
+        map[y][x] = '.';
+    }
+}
+
+for (let i = 0; i < 1024; i++) {
+    const [x, y] = input[i].split(',').map((st: string) => parseInt(st));
+    map[y][x] = '#'
+}
+
+function get(pos: Coord): string|number {
+    if (map[pos.y] && map[pos.y][pos.x]) {
+        return map[pos.y][pos.x];
+    }
+    return '#';
+}
+
+function set(pos: Coord, val: string|number): void {
+    map[pos.y][pos.x] = val;
+}
+
+function nextDir(dir: Dir): Dir {
+    const directions = [Dir.Up, Dir.Right, Dir.Down, Dir.Left];
+    const i = (directions.indexOf(dir) + 1) % directions.length;
+    return directions[i];
+}
+function prevDir(dir: Dir): Dir {
+    const directions = [Dir.Up, Dir.Right, Dir.Down, Dir.Left];
+    const i = directions.indexOf(dir) - 1;
+    if (i < 0) {
+        return directions[directions.length - 1];
+    }
+    return directions[i];
+}
+
+function printMap(path: Array<Coord> = []) {
+    const mapClone = map.slice().map((row: Array<string|number>) => row.slice());
+    path.forEach(({ x, y }) => {
+        mapClone[y][x] = 'O';
+    });
+    console.log(mapClone.map((row: Array<string|number>) => row.map((c) => typeof c === 'number' ? '.' : c).join('')).join("\n"));
+    console.log("\n");
+}
+
+function nextCoord(pos: Coord, direction: Dir): Coord {
+    return direction === Dir.Up ? { x: pos.x, y: pos.y - 1 }
+        : (direction === Dir.Right ? { x: pos.x + 1, y: pos.y }
+            : (direction === Dir.Down ? { x: pos.x, y: pos.y + 1 } : { x: pos.x - 1, y: pos.y })
+        );
+}
+
+function isDeadEnd(pos: Coord): boolean {
+    if ((pos.x === 0 && pos.y === 0) || (pos.x === width - 1 && pos.y === width - 1)) {
+        return false;
+    }
+    const adjs = [Dir.Up, Dir.Right, Dir.Down, Dir.Left].map((dir) => get(nextCoord(pos, dir))).join('');
+    return adjs === '###.'
+        || adjs === '##.#'
+        || adjs === '#.##'
+        || adjs === '.###';
+}
+
+function fillDeadEnd(pos: Coord): void {
+    set(pos, '#')
+    for (let dir of [Dir.Up, Dir.Right, Dir.Down, Dir.Left]) {
+        const next = nextCoord(pos, dir);
+        if (get(next) === '.') {
+            if (isDeadEnd(next)) {
+                fillDeadEnd(next);
+            }
+        }
+    };
+}
+printMap();
+
+for (let y = 0; y < height; y++) {
+    for (let x = 0; x < width; x++) {
+        const pos = { x, y };
+        const char = get(pos);
+        if (char !== '.') {
+            continue;
+        }
+        if (isDeadEnd(pos)) {
+            fillDeadEnd(pos);
+        }
+    }
+}
+
+printMap();
+
+for (let i = 1025; i < input.length; i++) {
+    const byte = input[i].split(',').map((c: string) => parseInt(c));
+    set({ x: byte[0], y: byte[1] }, '#');
+
+    for (let y = 0; y < height; y++) {
+        for (let x = 0; x < width; x++) {
+            const pos = { x, y };
+            let char = get(pos);
+            if (typeof char === 'number') {
+                set(pos, '.');
+            }
+        }
+    }
+
+    let finished = false;
+
+    function getScoresAfterPosition(pos: Coord, dir: Dir, path: Array<Coord> = []): void {
+        if (finished) {
+            return;
+        }
+        [dir, nextDir(dir), prevDir(dir)].forEach((newDir, i) => {
+            if (finished) {
+                return;
+            }
+            const next = nextCoord(pos, newDir);
+            if (next.x === width - 1 && next.y === height - 1) {
+                finished = true;
+                return;
+            }
+            const nextCell = get(next);
+            if (nextCell !== '#' && (typeof nextCell !== 'number' || nextCell > path.length) && !path.find(({ x, y }) => next.x === x && next.y === y)) {
+                set(next, path.length);
+                getScoresAfterPosition(next, newDir, [...path, next]);
+            }
+        });
+
+        return;
+    }
+
+    getScoresAfterPosition({ x: 0, y: 0 }, Dir.Right, [{ x: 0, y: 0 }]);
+
+    console.log(i, byte);
+    printMap();
+    if (!finished) {
+        console.log('blocked');
+        break;
+    }
+}