day 20

.aocrunner.json

@@ -300,16 +300,19 @@
     },
     {
       "part1": {
-        "solved": false,
-        "result": null,
-        "attempts": [],
-        "time": null
+        "solved": true,
+        "result": "1327",
+        "attempts": [
+          "19031047",
+          "1341"
+        ],
+        "time": 396.636417
       },
       "part2": {
-        "solved": false,
-        "result": null,
+        "solved": true,
+        "result": "985737",
         "attempts": [],
-        "time": null
+        "time": 409.185083
       }
     },
     {

README.md

@@ -30,7 +30,7 @@
 [![Day](https://badgen.net/badge/17/%E2%98%85%E2%98%85/green)](src/day17)
 [![Day](https://badgen.net/badge/18/%E2%98%85%E2%98%85/green)](src/day18)
 [![Day](https://badgen.net/badge/19/%E2%98%85%E2%98%85/green)](src/day19)
-![Day](https://badgen.net/badge/20/%E2%98%86%E2%98%86/gray)
+[![Day](https://badgen.net/badge/20/%E2%98%85%E2%98%85/green)](src/day20)
 ![Day](https://badgen.net/badge/21/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/22/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/23/%E2%98%86%E2%98%86/gray)
@@ -202,9 +202,9 @@ Both parts: 173.084ms
 
 ```
 Day 20
-Time part 1: -
-Time part 2: -
-Both parts: -
+Time part 1: 394.252ms
+Time part 2: 407.336ms
+Both parts: 801.588ms
 ```
 
 ```
@@ -243,8 +243,8 @@ Both parts: -
 ```
 
 ```
-Total stars: 38/50
-Total time: 176482.246ms
+Total stars: 40/50
+Total time: 177283.834ms
 ```
 
 <!--/RESULTS-->

src/day20/README.md

@@ -0,0 +1,9 @@
+# 🎄 Advent of Code 2024 - day 20 🎄
+
+## Info
+
+Task description: [link](https://adventofcode.com/2024/day/20)
+
+## Notes
+
+...

src/day20/index.ts

@@ -0,0 +1,93 @@
+import run from "aocrunner"
+
+const ints = (line: string) => [...line.matchAll(/\d+/g)].map(Number)
+const parseInput = (rawInput: string) =>
+  rawInput.split("\n").map((line) => line.split(""))
+
+const deltas: [Coord, Coord, Coord, Coord] = [
+  [0, 1], // right
+  [1, 0], // down
+  [0, -1], // left
+  [-1, 0], // up
+]
+
+type Coord = [number, number]
+
+function manhattan([ar, ac]: Coord, [br, bc]: Coord) {
+  return Math.abs(ar - br) + Math.abs(ac - bc)
+}
+
+const part1 = (rawInput: string, mustSave = 100, maxCheat = 2) => {
+  const input = parseInput(rawInput)
+  let S: Coord
+  let E: Coord
+  input.forEach((row, r) => {
+    row.forEach((cell, c) => {
+      if (cell === "S") S = [r, c]
+      if (cell === "E") E = [r, c]
+    })
+  })
+  let [r, c] = S
+  const path: Coord[] = [S]
+  while (true) {
+    const neighbors = deltas.map<Coord>(([dr, dc]) => [r + dr, c + dc])
+    const next = neighbors.find(([nr, nc]) => {
+      if (input[nr][nc] === "#") return false
+      return path.find(([pr, pc]) => pr === nr && pc === nc) === undefined
+    })
+    if (next === undefined) break
+    ;[r, c] = next
+    path.push(next)
+  }
+  let total = 0
+  for (let i = 0; i < path.length; i++) {
+    for (let j = i + mustSave; j < path.length; j++) {
+      const distance = manhattan(path[i], path[j])
+      if (distance <= maxCheat && j - i - distance >= mustSave) {
+        total++
+      }
+    }
+  }
+  return total
+}
+
+const part2 = (rawInput: string) => {
+  return part1(rawInput, 100, 20)
+}
+
+run({
+  part1: {
+    tests: [
+      // {
+      //   input: ``,
+      //   expected: "",
+      // },
+    ],
+    solution: part1,
+  },
+  part2: {
+    tests: [
+      // {
+      //   input: ``,
+      //   expected: "",
+      // },
+    ],
+    solution: part2,
+  },
+  trimTestInputs: true,
+  onlyTests: false,
+})
+
+function bold(text: string) {
+  return `\x1b[44;37;1m${text}\x1b[0m`
+}
+
+function memoize<T extends unknown[], U>(
+  fn: (...args: T) => U,
+): (...args: T) => U {
+  const cache = {} // Saves the values
+  return (...args) => {
+    const key = args.join("\n")
+    return cache[key] ?? (cache[key] = fn(...args))
+  }
+}

src/template/index.ts

@@ -1,7 +1,17 @@
 import run from "aocrunner"
 
+const ints = (line: string) => [...line.matchAll(/\d+/g)].map(Number)
 const parseInput = (rawInput: string) => rawInput
 
+const deltas: [Coord, Coord, Coord, Coord] = [
+  [ 0,  1], // right
+  [ 1,  0], // down
+  [ 0, -1], // left
+  [-1,  0], // up
+]
+
+type Coord = [number, number]
+
 const part1 = (rawInput: string) => {
   const input = parseInput(rawInput)
 
@@ -36,3 +46,15 @@ run({
   trimTestInputs: true,
   onlyTests: false,
 })
+
+function bold(text: string) {
+  return `\x1b[44;37;1m${text}\x1b[0m`
+}
+
+function memoize<T extends unknown[],U>(fn: (...args: T) => U): (...args: T) => U {
+  const cache = {} // Saves the values
+  return (...args) => {
+    const key = args.join('\n')
+    return cache[key] ?? (cache[key] = fn(...args))
+  }
+}