day 15 part 1

src/15/main.ts

@@ -0,0 +1,84 @@
+type Map = string[][];
+type Position = [x: number, y: number];
+type Move = "<" | "^" | ">" | "v";
+
+const moveMap = {
+  "<": [-1, 0],
+  "^": [0, -1],
+  ">": [1, 0],
+  "v": [0, 1],
+};
+
+function getNextPosition(current: Position, move: Move): Position {
+  const [dx, dy] = moveMap[move];
+  return [current[0] + dx, current[1] + dy];
+}
+
+export async function main(target = "input") {
+  const dirpath = new URL(".", import.meta.url).pathname;
+  const text = await Deno.readTextFile(`${dirpath}${target}.txt`);
+
+  const { map, moves, start } = text.split("\n").reduce((agg, line, idx) => {
+    if (line.match(/^[#.O@]+$/)) {
+      const row = line.split("");
+      const start = row.findIndex((cell) => cell === "@");
+      if (start !== -1) {
+        agg.start = [start, idx];
+        row[start] = ".";
+      }
+      agg.map.push(row);
+    } else if (line.match(/^[<^>v]+$/)) {
+      agg.moves.push(...(line.split("") as Move[]));
+    }
+
+    return agg;
+  }, { map: [] as Map, moves: [] as Move[], start: [0, 0] as Position });
+
+  let current = start;
+  moves.forEach((move) => {
+    const next = getNextPosition(current, move);
+
+    switch (map[next[1]]?.[next[0]]) {
+      case "#":
+        return;
+      case ".":
+        current = next;
+        return;
+      case "O": {
+        let nextInDirection = getNextPosition(next, move);
+        while (map[nextInDirection[1]]?.[nextInDirection[0]]) {
+          if (map[nextInDirection[1]][nextInDirection[0]] === "#") {
+            break;
+          }
+          if (map[nextInDirection[1]][nextInDirection[0]] === "O") {
+            nextInDirection = getNextPosition(nextInDirection, move);
+            continue;
+          }
+          if (map[nextInDirection[1]][nextInDirection[0]] === ".") {
+            map[nextInDirection[1]][nextInDirection[0]] = "O";
+            map[next[1]][next[0]] = ".";
+            current = next;
+            return;
+          }
+        }
+      }
+    }
+  });
+
+  const gpsSum = map.reduce((agg, row, y) => {
+    return agg + row.reduce((agg2, cell, x) => {
+      if (cell === "O") {
+        agg2 += y * 100 + x;
+      }
+      return agg2;
+    }, 0);
+  }, 0);
+
+  return { gpsSum };
+}
+
+if (import.meta.main) {
+  const startTime = performance.now();
+  console.log(await main());
+  console.log(`Elapsed: ${Math.round(performance.now() - startTime)}ms`);
+}

src/15/sample.txt

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+########
+#..O.O.#
+##@.O..#
+#...O..#
+#.#.O..#
+#...O..#
+#......#
+########
+
+<^^>>>vv<v>>v<<

src/15/sample2.txt

@@ -0,0 +1,21 @@
+##########
+#..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^<<^

src/15/test.ts

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+import { assertEquals } from "@std/assert";
+import { main } from "./main.ts";
+
+const target = "sample";
+
+Deno.test(`correct GPS sum for ${target}`, async () => {
+  const result = await main(target);
+  assertEquals(result.gpsSum, 2028);
+});
+
+Deno.test(`correct GPS sum for sample2`, async () => {
+  const result = await main("sample2");
+  assertEquals(result.gpsSum, 10092);
+});
+
+// Deno.test(`correct placeholder2 for ${target}`, async () => {
+//   const result = await main(target);
+//   assertEquals(result.gpsSum, 0);
+// });