day 6, buggy part 2

src/day06/README.md

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+# 🎄 Advent of Code 2024 - day 6 🎄
+
+## Info
+
+Task description: [link](https://adventofcode.com/2024/day/6)
+
+## Notes
+
+...

src/day06/index.ts

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+import run from "aocrunner"
+
+const parseInput = (rawInput: string) => rawInput.split('\n')
+
+const part1 = (rawInput: string) => {
+  const input = parseInput(rawInput)
+  const rawCol = rawInput.indexOf('^')
+  let width = rawInput.indexOf('\n')
+  let position = [Math.floor(rawCol / (width + 1)), rawCol % (width + 1)]
+  let visited = new Set<string>()
+  const directions = [
+    [-1,0],
+    [0,1],
+    [1,0],
+    [0,-1]
+  ]
+  let dir = 0
+  while(true) {
+    visited.add(position.join())
+    const nextPosition = [position[0] + directions[dir][0], position[1] + directions[dir][1]]
+    const next = (input[nextPosition[0]] ?? [])[nextPosition[1]]
+    if (next === undefined) {
+      break // done!
+    }
+    if (next === "#") {
+      dir = (dir + 1) % 4
+      continue
+    }
+    position = nextPosition
+  }
+  return visited.size
+}
+
+const part2 = (rawInput: string) => {
+  const input = parseInput(rawInput)
+  const rawCol = rawInput.indexOf('^')
+  let width = rawInput.indexOf('\n')
+  const directions = [
+    [-1,0],
+    [0,1],
+    [1,0],
+    [0,-1]
+  ]
+  let obstructions = new Set<string>()
+  const walk = (
+    initialPosition: number[],
+    tempObstacle?: [number, number],
+    initialVisited = new Set<string>,
+    initialDir = 0
+  ) => {
+    let position = [...initialPosition]
+    let visited = new Set(initialVisited)
+    let dir = initialDir
+    while(true) {
+      const key = [...position, dir].join()
+      if (visited.has(key)) {
+        // we have entered a loop!
+        obstructions.add(tempObstacle.join())
+        return
+      }
+      const nextPosition: [number, number] = [position[0] + directions[dir][0], position[1] + directions[dir][1]]
+      const next = (input[nextPosition[0]] ?? [])[nextPosition[1]]
+      if (next === undefined) {
+        // we are done!
+        return obstructions.size
+      }
+      if (tempObstacle == null && next != "#" && !obstructions.has(nextPosition.join())) {
+        walk(position, nextPosition, visited, dir)
+      }
+      visited.add(key)
+      if (next === "#" || (tempObstacle != null && nextPosition.join() === tempObstacle.join())) {
+        dir = (dir + 1) % 4
+        continue
+      }
+      position = nextPosition
+    }
+  }
+  return walk([Math.floor(rawCol / (width + 1)), rawCol % (width + 1)])
+}
+
+run({
+//   part1: {
+//     tests: [
+//       {
+//         input: `....#.....
+// .........#
+// ..........
+// ..#.......
+// .......#..
+// ..........
+// .#..^.....
+// ........#.
+// #.........
+// ......#...`,
+//         expected: 41,
+//       },
+//     ],
+//     solution: part1,
+//   },
+  part2: {
+    tests: [
+      {
+        input: `....#.....
+.........#
+..........
+..#.......
+.......#..
+..........
+.#..^.....
+........#.
+#.........
+......#...`,
+        expected: 6,
+      },
+    ],
+    solution: part2,
+  },
+  trimTestInputs: true,
+  onlyTests: false,
+})