Day 15

2024/15/index.ts

@@ -0,0 +1,89 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+interface Coord {
+    x: number,
+    y: number,
+};
+
+const [mapStr, movementsStr] = input.split("\n\n");
+
+const map: Array<Array<string>> = mapStr.split("\n").map((row: string) => row.split(''));
+const movements = movementsStr.split("\n").join('');
+
+const width = map[0].length;
+const height = map.length;
+
+const robotIndex = mapStr.indexOf('@');
+let robotPos = { x: robotIndex % (width + 1), y: Math.floor(robotIndex / height) };
+map[robotPos.y][robotPos.x] = '.';
+
+function nextCoord(pos: Coord, dir: '^'|'>'|'<'|'v'): Coord|null {
+    const newCoord = {
+        "^": { x: pos.x, y: pos.y - 1 },
+        ">": { x: pos.x + 1, y: pos.y },
+        "v": { x: pos.x, y: pos.y + 1 },
+        "<": { x: pos.x - 1, y: pos.y },
+    }[dir];
+
+    if (newCoord.x < 0 || newCoord.x >= width || newCoord.y < 0 || newCoord.y > height) {
+        return null;
+    }
+    return newCoord;
+}
+
+function printMap() {
+    const mapClone = map.slice().map((row: Array<string>) => row.slice());
+    mapClone[robotPos.y][robotPos.x] = '@';
+    console.log(mapClone.map((row: Array<string>) => row.join('')).join("\n"));
+}
+
+printMap();
+
+for (let i = 0; i < movements.length; i++) {
+    const direction = movements[i];
+
+    const nextRobotPosition = nextCoord(robotPos, direction);
+    if (!nextRobotPosition) {
+        continue;
+    }
+    let value = map[nextRobotPosition.y][nextRobotPosition.x];
+    if (value === '#') {
+        continue;
+    }
+    let boxes = [];
+    let boxPos = {...nextRobotPosition};
+    while (value === 'O') {
+        boxes.push(boxPos);
+        const nextBoxCoord = nextCoord(boxPos, direction);
+        if (!nextBoxCoord) {
+            break;
+        }
+        boxPos = nextBoxCoord;
+        value = map[boxPos.y][boxPos.x];
+    }
+    if (boxes.length && value !== '#') {
+        boxes.reverse().forEach((pos) => {
+            map[pos.y][pos.x] = '.';
+            const newPos = nextCoord(pos, direction)!;
+            map[newPos.y][newPos.x] = 'O';
+        })
+    } else if (boxes.length) {
+        continue;
+    }
+    robotPos = nextRobotPosition;
+    printMap();
+}
+
+let sum = 0;
+
+map.forEach((row, y) => {
+    row.forEach((val, x) => {
+        if (val === 'O') {
+            sum += ((y * 100) + x);
+        }
+    });
+});
+
+console.log(sum);