Day 2

Author: foof

1/star-2.js

@@ -6,7 +6,7 @@ const findFrequency = (inputRows) => {
     let currentFrequency = 0
     const visitedFrequencies = []
     while (true) {
-        for (let row of inputRows) {
+        for (const row of inputRows) {
             currentFrequency += parseInt(row)
             if (visitedFrequencies.includes(currentFrequency)) {
                 return currentFrequency

2/input.txt

@@ -0,0 +1,250 @@
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2/star-3.js

@@ -0,0 +1,26 @@
+const fs = require('fs')
+
+const inputRows = fs.readFileSync('./input.txt', 'utf8').split("\n")
+
+let doubles = 0
+let triples = 0
+for (const row of inputRows) {
+    let charCount = {}
+    for (const char of row.split('')) {
+        charCount.hasOwnProperty(char) ? charCount[char]++ : charCount[char] = 1
+    }
+
+    let double = 0
+    let triple = 0
+    for (const char in charCount) {
+        if (charCount[char] === 2) double = 1
+        if (charCount[char] === 3) triple = 1
+    }
+
+    doubles += double
+    triples += triple
+}
+
+console.log('doubles', doubles)
+console.log('triples', triples)
+console.log('checksum', triples * doubles)

2/star-4.js

@@ -0,0 +1,37 @@
+const fs = require('fs')
+
+const inputRows = fs.readFileSync('./input.txt', 'utf8').split("\n")
+
+function compareWords(id1, id2) {
+    const chars1 = id1.split('')
+    const chars2 = id2.split('')
+    let differences = 0
+    for (let i = 0; i < chars1.length; i++) {
+        if (chars1[i] !== chars2[i]) differences++
+    }
+    return differences
+}
+
+function removeDifferences(id1, id2) {
+    const chars1 = id1.split('')
+    const chars2 = id2.split('')
+    let result = ''
+    for (let i = 0; i < chars1.length; i++) {
+        if (chars1[i] === chars2[i]) result += chars1[i]
+    }
+    return result
+}
+
+function findSimilarBoxes(boxIds) {
+    for (const id1 of boxIds) {
+        for (const id2 of boxIds) {
+            const differences = compareWords(id1, id2)
+            if (differences === 1) {
+                return removeDifferences(id1, id2)
+            }
+        }
+    }
+}
+
+const result = findSimilarBoxes(inputRows)
+console.log(result)