2022 day 9 and add utils

1 files changed, 61 insertions, 0 deletions

diff --git a/aoc_2022/day-09/part_2.ts b/aoc_2022/day-09/part_2.ts
new file mode 100644
index 0000000..5b0df2a
--- /dev/null
+++ b/aoc_2022/day-09/part_2.ts
@@ -0,0 +1,61 @@
+import { JSONSet, Vec2, l2Norm, isDiagAdj } from "@/utils";
+
+export const main = async (lines: string[]): Promise<number | string> => {
+  const knots: Vec2[] = Array(10)
+    .fill(null)
+    .map(() => ({ x: 0, y: 0 }));
+
+  const visited: JSONSet<Vec2> = new JSONSet();
+  visited.add(knots[0]);
+
+  for (const step of lines) {
+    const [dir, steps_s] = step.split(" ");
+    const steps = parseInt(steps_s);
+
+    for (let i = 0; i < steps; ++i) {
+      if (dir === "U") knots[0].y += 1;
+      if (dir === "L") knots[0].x -= 1;
+      if (dir === "R") knots[0].x += 1;
+      if (dir === "D") knots[0].y -= 1;
+
+      for (let knotidx = 1; knotidx < knots.length; knotidx++) {
+        const [head, tail] = [knots[knotidx - 1], knots[knotidx]];
+
+        if (!isDiagAdj(head, tail)) {
+          if (head.y - tail.y === 0) {
+            tail.x += Math.floor((head.x - tail.x) / 2);
+          } else if (head.x - tail.x === 0) {
+            tail.y += Math.floor((head.y - tail.y) / 2);
+          } else {
+            tail.x += head.x - tail.x > 0 ? 1 : -1;
+            tail.y += head.y - tail.y > 0 ? 1 : -1;
+          }
+        }
+
+        if (knotidx === knots.length - 1) {
+          visited.add(tail);
+        }
+      }
+    }
+  }
+
+  return visited.size;
+};
+
+//
+
+const isrun = process.argv.length > 1 && process.argv[1] === import.meta.path;
+if (isrun) {
+  const file = Bun.file("./problem.txt");
+  const text = await file.text();
+  const lines = text.split("\n").filter((x) => x && x.length);
+
+  console.log("=== COMPUTATION ===\n");
+
+  const answer = await main(lines);
+
+  console.log("\n=== /COMPUTATION ===\n");
+
+  console.log("=== ANSWER TO P2 ===");
+  console.log(answer);
+}