Day 8

2024/08/index.ts

@@ -0,0 +1,72 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+interface Coord { x: number, y: number };
+
+const nodes: { [key: string]: Array<Coord> } = {};
+const antiNodes: Array<Coord> = [];
+
+let x = 0;
+let y = 0;
+for (let i = 0; i < input.length; i++) {
+    const char = input[i];
+    if (char === "\n") {
+        y++;
+        x = 0;
+        continue;
+    }
+    if (char !== '.') {
+        if (!nodes[char]) {
+            nodes[char] = [];
+        }
+        nodes[char].push({ x, y });
+    }
+    x++;
+}
+const width = x;
+const height = y + 1;
+
+function coordsMatch(a: Coord, b: Coord) {
+    return a.x === b.x && a.y === b.y;
+}
+
+function offMap(coord: Coord) {
+    return coord.x >= width
+        || coord.x < 0
+        || coord.y >= height
+        || coord.y < 0;
+}
+
+function antiNodeExists(coord: Coord) {
+    return antiNodes.some((pos) => coordsMatch(pos, coord));
+}
+
+const total = Object.keys(nodes).length;
+let current = 0;
+
+for (let key of Object.keys(nodes)) {
+    current++;
+    console.log(Math.floor(current / total * 100));
+    const n = nodes[key];
+    for (let i = 0; i < n.length; i++) {
+        const nodeA = n[i];
+        const otherNodes = [...n.slice(0, i), ...n.slice(i+1)];
+        for (let j = 0; j < otherNodes.length; j++) {
+            const nodeB = otherNodes[j];
+            const xDiff = nodeB.x - nodeA.x;
+            const yDiff = nodeB.y - nodeA.y;
+            const antiXDiff = -1 * xDiff;
+            const antiYDiff = -1 * yDiff;
+            let antiCoord = { x: nodeB.x + antiXDiff, y: nodeB.y + antiYDiff };
+            while (!offMap(antiCoord)) {
+                if (!antiNodeExists(antiCoord)) {
+                    antiNodes.push(antiCoord);
+                }
+                antiCoord = { x: antiCoord.x + antiXDiff, y: antiCoord.y + antiYDiff };
+            }
+        }
+    }
+}
+
+console.log(antiNodes.length);