day 4, messy

src/day04/README.md

@@ -0,0 +1,9 @@
+# 🎄 Advent of Code 2024 - day 4 🎄
+
+## Info
+
+Task description: [link](https://adventofcode.com/2024/day/4)
+
+## Notes
+
+...

src/day04/index.ts

@@ -0,0 +1,169 @@
+import run from "aocrunner"
+
+const parseInput = (rawInput: string) => {
+  return rawInput.split('\n').map(line => line.split(''))
+}
+
+const directions = ["down","right","dl","dr"] as const
+type Direction = typeof directions[number]
+type Prospect1 = {
+  letters: string
+  direction: Direction
+  next: [number, number]
+}
+type Coord = Prospect1['next']
+const getNext = (dir: Direction, [row, col]: Coord): Coord => {
+  switch(dir) {
+    case "down": {return [row+1, col]}
+    case "right": {return [row, col+1]}
+    case "dl": {return [row+1, col-1]}
+    case "dr": {return [row+1, col+1]}
+  }
+}
+
+const part1 = (rawInput: string) => {
+  const input = parseInput(rawInput)
+  let total = 0
+  let prospects: Prospect1[] = []
+  input.forEach((line, row) => {
+    line.forEach((letter, col) => {
+      prospects = prospects.map((prospect) => {
+        const {
+          direction,
+          letters,
+          next
+        } = prospect
+        if (next[0] < row) return null
+        if (next[0] === row && next[1] === col) {
+          const nextLetters = letters + letter
+          if (["XMAS","SAMX"].includes(nextLetters)) {
+            total += 1
+            return null
+          }
+          if (["XMA","SAM","XM","SA"].includes(nextLetters)) {
+            return {
+              letters: nextLetters,
+              direction: direction,
+              next: getNext(direction, next)
+            }
+          }
+        }
+        return prospect
+      }).filter(prospect => prospect != null)
+      if ("XMAS".includes(letter)) {
+        directions.forEach(direction => {
+          prospects.push({
+            letters: letter,
+            direction,
+            next: getNext(direction, [row, col])
+          })
+        })
+      }
+    })
+  })
+  return total
+}
+
+type Prospect2 = {
+  letters: string
+  direction: Direction
+  next: [number, number]
+  center: [number, number]
+}
+
+const part2 = (rawInput: string) => {
+  const input = parseInput(rawInput)
+  let centers = new Map<string, number>()
+  let prospects: Prospect2[] = []
+  let total = 0
+  input.forEach((line, row) => {
+    line.forEach((letter, col) => {
+      prospects = prospects.map((prospect) => {
+        const {
+          direction,
+          letters,
+          next
+        } = prospect
+        if (next[0] < row) return null
+        if (next[0] === row && next[1] === col) {
+          const nextLetters = letters + letter
+          if (["MAS","SAM"].includes(nextLetters)) {
+            const key = prospect.center.join(",")
+            if (centers.has(key)) { total++ }
+            centers.set(key, 1)
+            return null
+          }
+          if (["MA","SA"].includes(nextLetters)) {
+            return {
+              ...prospect,
+              letters: nextLetters,
+              next: getNext(direction, next),
+            }
+          }
+        }
+        return prospect
+      }).filter(prospect => prospect != null)
+      if ("XMAS".includes(letter)) {
+        ["dl" as const, "dr" as const].forEach(direction => {
+          const center = getNext(direction, [row, col])
+          prospects.push({
+            letters: letter,
+            direction,
+            next: center,
+            center,
+          })
+        })
+      }
+    })
+  })
+  return total
+}
+
+run({
+  part1: {
+    tests: [
+      {
+        input: `..X...
+.SAMX.
+.A..A.
+XMAS.S
+.X....`,
+        expected: 4
+      },
+      {
+        input: `MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX`,
+        expected: 18,
+      },
+    ],
+    solution: part1,
+  },
+  part2: {
+    tests: [
+      {
+        input: `MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX`,
+        expected: 9,
+      },
+    ],
+    solution: part2,
+  },
+  trimTestInputs: true,
+  onlyTests: false,
+})