day 3

src/day03/README.md

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+# 🎄 Advent of Code 2021 - day 3 🎄
+
+## Info
+
+Task description: [link](https://adventofcode.com/2021/day/3)
+
+## Notes
+
+...

src/day03/index.js

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+import run from "aocrunner"
+
+const parseInput = (rawInput) => rawInput.trim().split`\n`
+
+const part1 = (rawInput) => {
+  const input = parseInput(rawInput)
+  const ones = []
+  input.forEach((l) => {
+    ;[...l].forEach((x, i) => {
+      if (x === "1") {
+        ones[i] = (ones[i] || 0) + 1
+      }
+    })
+  })
+  const gamma = parseInt(
+    ones.reduce((acc, p) => acc + (p >= input.length / 2 ? "1" : "0"), ""),
+    2,
+  )
+  const epsilon = parseInt(
+    ones.reduce((acc, p) => acc + (p < input.length / 2 ? "1" : "0"), ""),
+    2,
+  )
+  return gamma * epsilon
+}
+
+function countOnes(input) {
+  const ones = []
+  input.forEach((l) => {
+    ;[...l].forEach((x, i) => {
+      if (x === "1") {
+        ones[i] = (ones[i] || 0) + 1
+      }
+    })
+  })
+  return ones
+}
+
+const part2 = (rawInput) => {
+  const input = parseInput(rawInput)
+  let oxyQueue = input.slice()
+  for (let place = 0; oxyQueue.length !== 1; place++) {
+    const ones = countOnes(oxyQueue)
+    oxyQueue = oxyQueue.filter((val) => {
+      const most = ones[place] >= oxyQueue.length / 2 ? "1" : "0"
+      return val[place] === most
+    })
+  }
+  const oxy = parseInt(oxyQueue[0], 2)
+
+  let co2Queue = input.slice()
+  for (let place = 0; co2Queue.length !== 1; place++) {
+    const ones = countOnes(co2Queue)
+    co2Queue = co2Queue.filter(
+      (val) => val[place] === (ones[place] < co2Queue.length / 2 ? "1" : "0"),
+    )
+  }
+  const co2 = parseInt(co2Queue[0], 2)
+
+  return oxy * co2
+}
+
+run({
+  part1: {
+    tests: [
+      {
+        input: `00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010`,
+        expected: 198,
+      },
+    ],
+    solution: part1,
+  },
+  part2: {
+    tests: [
+      {
+        input: `00100
+11110
+10110
+10111
+10101
+01111
+00111
+11100
+10000
+11001
+00010
+01010`,
+        expected: 230,
+      },
+    ],
+    solution: part2,
+  },
+  trimTestInputs: true,
+})