day 15

days/15/main.ts

@@ -0,0 +1,103 @@
+import { loadInput } from "utils";
+
+export function part1(input: Array<string>) {
+  const { walls, boxes, initialRobotPosition, moves, width, height } =
+    parseInput(input);
+  let robotPosition = initialRobotPosition;
+  //   console.log("Initial state:");
+  for (const move of moves) {
+    // print(robotPosition, walls, boxes, width, height);
+    // console.log(`Move ${move}:`);
+    const directionVector =
+      directionVectors[move as unknown as keyof typeof directionVectors]!;
+    const potentialNewRobotPosition = robotPosition + directionVector;
+    if (walls.has(potentialNewRobotPosition)) continue;
+    if (!boxes.has(potentialNewRobotPosition)) {
+      robotPosition = potentialNewRobotPosition;
+      continue;
+    }
+    for (
+      let next = potentialNewRobotPosition + directionVector;
+      !walls.has(next);
+      next += directionVector
+    ) {
+      if (boxes.has(next)) {
+        continue;
+      }
+      boxes.delete(potentialNewRobotPosition);
+      boxes.add(next);
+      robotPosition = potentialNewRobotPosition;
+      break;
+    }
+  }
+  //   print(robotPosition, walls, boxes, width, height);
+  return boxes.values().reduce((acc, gps) => acc + gps, 0);
+}
+
+export function part2(input: Array<string>) {
+  return 0;
+}
+
+function parseInput(input: Array<string>) {
+  const walls = new Set<number>();
+  const boxes = new Set<number>();
+  let initialRobotPosition = -1;
+  const delimiterIndex = input.indexOf("");
+  const moves = input.slice(delimiterIndex + 1).join("");
+  const map = input.slice(0, delimiterIndex);
+  for (let y = 0; y < map.length; y++) {
+    const row = map[y];
+    for (let x = 0; x < row.length; x++) {
+      const char = row[x];
+      if (char === ".") continue;
+      else if (char === "#") walls.add(gpsCoordinate(x, y));
+      else if (char === "O") boxes.add(gpsCoordinate(x, y));
+      else if (char === "@") initialRobotPosition = gpsCoordinate(x, y);
+    }
+  }
+  return {
+    walls,
+    boxes,
+    initialRobotPosition,
+    moves,
+    width: map.length,
+    height: map[0].length,
+  };
+}
+
+const directionVectors = {
+  "^": gpsCoordinate(0, -1),
+  ">": gpsCoordinate(1, 0),
+  "v": gpsCoordinate(0, 1),
+  "<": gpsCoordinate(-1, 0),
+};
+
+function gpsCoordinate(x: number, y: number) {
+  return 100 * y + x;
+}
+
+function print(
+  robot: number,
+  walls: Set<number>,
+  boxes: Set<number>,
+  width: number,
+  height: number,
+) {
+  for (let y = 0; y < height; y++) {
+    let row = "";
+    for (let x = 0; x < width; x++) {
+      const gps = gpsCoordinate(x, y);
+      if (walls.has(gps)) row += "#";
+      else if (boxes.has(gps)) row += "O";
+      else if (robot === gps) row += "@";
+      else row += ".";
+    }
+    console.log(row);
+  }
+  console.log("");
+}
+
+if (import.meta.main) {
+  console.log(part1(await loadInput(15)));
+  console.log(part2(await loadInput(15)));
+}

days/15/main_test.ts

@@ -0,0 +1,61 @@
+import { expect } from "@std/expect";
+import { describe, it } from "@std/testing/bdd";
+import { part1, part2 } from "./main.ts";
+import { loadInput } from "utils";
+
+describe("day 15 example", () => {
+  it("part 1 small", () => {
+    expect(part1([
+      "########",
+      "#..O.O.#",
+      "##@.O..#",
+      "#...O..#",
+      "#.#.O..#",
+      "#...O..#",
+      "#......#",
+      "########",
+      "",
+      "<^^>>>vv<v>>v<<",
+    ])).toBe(2028);
+  });
+
+  it("part 1 large", () => {
+    expect(part1([
+      "##########",
+      "#..O..O.O#",
+      "#......O.#",
+      "#.OO..O.O#",
+      "#[email protected].#",
+      "#O#..O...#",
+      "#O..O..O.#",
+      "#.OO.O.OO#",
+      "#....O...#",
+      "##########",
+      "",
+      "<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^",
+      "vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v",
+      "><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<",
+      "<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^",
+      "^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><",
+      "^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^",
+      ">^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^",
+      "<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>",
+      "^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>",
+      "v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^",
+    ])).toBe(10092);
+  });
+
+  it.ignore("part 2", () => {
+    expect(part2([])).toBe(-1);
+  });
+});
+
+describe("day 15 solution", () => {
+  it("part 1", async () => {
+    expect(part1(await loadInput(15))).toBe(1441031);
+  });
+
+  it.ignore("part 2", async () => {
+    expect(part2(await loadInput(15))).toBe(-1);
+  });
+});

days/mod.ts

@@ -3,7 +3,7 @@ type Solution = { part1: PartFunction; part2: PartFunction };
 
 const days = new Map<number, Solution>();
 
-for (const day of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14]) {
+for (const day of [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15]) {
   days.set(day, await import(`./${day}/main.ts`));
 }