day 9

.aocrunner.json

@@ -125,16 +125,16 @@
     },
     {
       "part1": {
-        "solved": false,
-        "result": null,
+        "solved": true,
+        "result": "444",
         "attempts": [],
-        "time": null
+        "time": 12.26
       },
       "part2": {
-        "solved": false,
-        "result": null,
+        "solved": true,
+        "result": "1168440",
         "attempts": [],
-        "time": null
+        "time": 22.72
       }
     },
     {

README.md

@@ -19,7 +19,7 @@
 [![Day](https://badgen.net/badge/06/%E2%98%85%E2%98%85/green)](src/day06)
 [![Day](https://badgen.net/badge/07/%E2%98%85%E2%98%85/green)](src/day07)
 [![Day](https://badgen.net/badge/08/%E2%98%85%E2%98%85/green)](src/day08)
-![Day](https://badgen.net/badge/09/%E2%98%86%E2%98%86/gray)
+[![Day](https://badgen.net/badge/09/%E2%98%85%E2%98%85/green)](src/day09)
 ![Day](https://badgen.net/badge/10/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/11/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/12/%E2%98%86%E2%98%86/gray)
@@ -125,9 +125,9 @@ Both parts: 19.64ms
 
 ```
 Day 09
-Time part 1: -
-Time part 2: -
-Both parts: -
+Time part 1: 12.26ms
+Time part 2: 22.72ms
+Both parts: 34.98ms
 ```
 
 ```
@@ -243,8 +243,8 @@ Both parts: -
 ```
 
 ```
-Total stars: 16/50
-Total time: 398.31999999999994ms
+Total stars: 18/50
+Total time: 433.29999999999995ms
 ```
 
 <!--/RESULTS-->

src/day09/README.md

@@ -0,0 +1,9 @@
+# 🎄 Advent of Code 2021 - day 9 🎄
+
+## Info
+
+Task description: [link](https://adventofcode.com/2021/day/9)
+
+## Notes
+
+...

src/day09/index.js

@@ -0,0 +1,83 @@
+import run from "aocrunner"
+
+const parseInput = (rawInput) =>
+  rawInput.trim().split`\n`.map((y) => [...y].map((x) => +x))
+
+function risk(x, y, map) {
+  let base = map[y][x]
+  if (map[y - 1] && map[y - 1][x] <= base) return undefined
+  if (map[y + 1] && map[y + 1][x] <= base) return undefined
+  if (map[y][x - 1] <= base) return undefined
+  if (map[y][x + 1] <= base) return undefined
+  return base
+}
+
+const part1 = (rawInput) => {
+  const input = parseInput(rawInput)
+  let lowSum = 0
+  for (const y in input) {
+    for (const x in input[y]) {
+      const r = risk(+x, +y, input)
+      lowSum += r + 1 || 0
+    }
+  }
+  return lowSum
+}
+
+const part2 = (rawInput) => {
+  const input = parseInput(rawInput)
+  const basinSizes = []
+  for (const Y in input) {
+    for (const X in input[Y]) {
+      const x = +X,
+        y = +Y
+      const r = risk(x, y, input)
+      if (r !== undefined) {
+        const basin = []
+        function spread(y, x) {
+          const key = `${y},${x}`
+          if (input[y][x] === 9 || basin.includes(key)) return
+          basin.push(key)
+          if (input[y - 1]) spread(y - 1, x)
+          if (input[y + 1]) spread(y + 1, x)
+          if (input[y][x - 1] !== undefined) spread(y, x - 1)
+          if (input[y][x + 1] !== undefined) spread(y, x + 1)
+        }
+        spread(y, x)
+        basinSizes.push(basin.length)
+      }
+    }
+  }
+  basinSizes.sort((a, b) => b - a)
+  return basinSizes[0] * basinSizes[1] * basinSizes[2]
+}
+
+run({
+  part1: {
+    tests: [
+      {
+        input: `2199943210
+3987894921
+9856789892
+8767896789
+9899965678`,
+        expected: 15,
+      },
+    ],
+    solution: part1,
+  },
+  part2: {
+    tests: [
+      {
+        input: `2199943210
+3987894921
+9856789892
+8767896789
+9899965678`,
+        expected: 1134,
+      },
+    ],
+    solution: part2,
+  },
+  trimTestInputs: true,
+})