feat: Solution Day 15, both stars ⭐ 🌟 TypeScript

2021/deno/day-15.ts

@@ -0,0 +1,120 @@
+function norm(x: number, y: number, width: number) {
+  return x + y * width;
+}
+
+function createMatrix<T>(size: number, init: () => T): T[] {
+  return Array.from({ length: size }, init);
+}
+
+function calcAdj(width: number, height: number) {
+  const adj = createMatrix<number[]>(width * height, () => []);
+
+  for (let y = 0; y < height; y++) {
+    for (let x = 0; x < width; x++) {
+      let index = norm(x, y, width);
+      if (y + 1 < height) {
+        // down
+        adj[index].push(norm(x, y + 1, width));
+      }
+      if (x + 1 < width) {
+        // right
+        adj[index].push(norm(x + 1, y, width));
+      }
+      if (x > 0) {
+        // left
+        adj[index].push(norm(x - 1, y, width));
+      }
+      if (y > 0) {
+        // up
+        adj[index].push(norm(x, y - 1, width));
+      }
+    }
+  }
+
+  return adj;
+}
+
+function bfs(start: number, adj: number[][], map: number[], size: number) {
+  const q: number[] = [];
+  const visited = createMatrix(size, () => false);
+  const risks = createMatrix(size, () => Infinity);
+
+  visited[start] = true;
+  risks[start] = 0;
+  q.push(start);
+
+  while (true) {
+    const current = q.shift();
+
+    if (current == null) break;
+
+    for (const vec of adj[current]) {
+      if (vec === start) continue;
+
+      const next = risks[current] + map[vec];
+
+      if (next < risks[vec]) {
+        risks[vec] = next;
+        q.push(vec);
+        visited[vec] = true;
+      }
+
+      if (visited[vec]) continue;
+    }
+  }
+
+  return risks;
+}
+
+const input = await Deno.readTextFile("./input/day-15.in");
+// const input = await Deno.readTextFile("./input/example.in");
+
+const rows = input.split("\n");
+
+/**
+ * Part One
+ */
+const height = rows.length;
+const width = rows[0].length;
+
+const grid = rows.map((row) => row.split("").map(Number)).flat(1);
+
+const adj = calcAdj(width, height);
+
+const start = 0;
+const end = norm(width - 1, height - 1, width);
+
+const paths = bfs(start, adj, grid, width * height);
+
+console.log("Part One:", paths[end]);
+
+/**
+ * Part Two
+ */
+const megaGrid = Array.from({ length: 5 * height * 5 * width }, () => 0);
+
+for (let y = 0; y < 5 * height; y++) {
+  for (let x = 0; x < 5 * width; x++) {
+    let value =
+      Math.floor(y / height) +
+      Math.floor(x / width) +
+      grid[norm(x % width, y & height, width)];
+
+    while (value > 9) {
+      value = value - 9;
+    }
+
+    megaGrid[norm(x, y, 5 * width)] = value;
+  }
+}
+
+const megaWidth = 5 * height;
+const megaHeight = 5 * width;
+const megaAdj = calcAdj(megaWidth, megaHeight);
+
+const megaSize = megaWidth * megaHeight;
+const megaPaths = bfs(start, megaAdj, megaGrid, megaSize);
+
+const megaEnd = norm(megaWidth - 1, megaHeight - 1, megaWidth);
+
+console.log("Part Two:", megaPaths[megaEnd]);