1 files changed, 75 insertions, 0 deletions
diff --git a/aoc_2022/day-09/part_1.ts b/aoc_2022/day-09/part_1.ts
new file mode 100644
index 0000000..b255aca
--- /dev/null
+++ b/aoc_2022/day-09/part_1.ts
@@ -0,0 +1,75 @@
+import { JSONSet } from "@/utils";
+
+type Point = {
+  x: number;
+  y: number;
+};
+
+const distance = (p1: Point, p2: Point) =>
+  Math.sqrt(Math.pow(p2.x - p1.x, 2) + Math.pow(p2.y - p1.y, 2));
+
+const isDiagAdj = (p1: Point, p2: Point) => distance(p1, p2) <= Math.sqrt(2);
+
+export const main = async (lines: string[]): Promise<number | string> => {
+  const knots: Point[] = Array(2)
+    .fill(null)
+    .map(() => ({ x: 0, y: 0 }));
+
+  const visited: JSONSet<Point> = 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 (dir === "U") {
+            tail.x = head.x;
+            tail.y = head.y - 1;
+          }
+          if (dir === "L") {
+            tail.x = head.x + 1;
+            tail.y = head.y;
+          }
+          if (dir === "R") {
+            tail.x = head.x - 1;
+            tail.y = head.y;
+          }
+          if (dir === "D") {
+            tail.x = head.x;
+            tail.y = head.y + 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 P1 ===");
+  console.log(answer);
+}