Day 10

2025-07-27 08:16:08 +00:00 · 2020-12-09 23:21:09 -05:00 · 2020-12-09 23:21:09 -05:00 · 6aaf867952
commit 6aaf867952
parent 593288b359
3 changed files with 193 additions and 0 deletions
--- a/solutions/day10/input.txt
+++ b/solutions/day10/input.txt
@ -0,0 +1,102 @@
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--- a/solutions/day10/solution.js
+++ b/solutions/day10/solution.js
@ -0,0 +1,48 @@
+const path = require('path')
+const { read, position } = require('promise-path')
+const fromHere = position(__dirname)
+const report = (...messages) => console.log(`[${require(fromHere('../../package.json')).logName} / ${__dirname.split(path.sep).pop()}]`, ...messages)
+
+async function run () {
+  const input = (await read(fromHere('input.txt'), 'utf8')).trim().split('\n').map(x => 1 * x).sort((a, b) => b - a)
+  input.push(0)
+  input.unshift(input[0] + 3)
+
+  solveForFirstStar(input)
+  solveForSecondStar(input)
+}
+
+function solveForFirstStar (input) {
+  let ones = 0
+  let threes = 0
+  input.forEach((s, i, S) => {
+    const diff = s - S[i + 1]
+    if (diff === 1) {
+      ones++
+    }
+    if (diff === 3) {
+      threes++
+    }
+  })
+  const solution = ones * threes
+  report('Solution 1:', solution)
+}
+
+function solveForSecondStar (input) {
+  const choices = []
+  input.forEach((s, i, S) => {
+    choices[i] = i === 0 ? 1 : 0
+    for (let j = 1; ; j++) {
+      if (S[i - j] - s <= 3) {
+        choices[i] += choices[i - j]
+      } else {
+        break
+      }
+    }
+  })
+
+  const solution = choices[choices.length - 1]
+  report('Solution 2:', solution)
+}
+
+run()
--- a/solutions/day10/viewer.html
+++ b/solutions/day10/viewer.html
@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Solution Viewer</title>
+    <style>
+      html, body { font-family: sans-serif; }
+      pre { border-radius: 0.5em; padding: 0.5em; background: #eee; }
+    </style>
+    <script src="https://cdn.jsdelivr.net/npm/axios/dist/axios.min.js"></script>
+    <script src="https://cdn.jsdelivr.net/npm/vue"></script>
+  </head>
+  <body>
+    <div id="viewer">
+      <h1>Solution Viewer ({{ solutionTitle }})</h1>
+      <p>For interesting problems; this page can be used as a dynamic viewer.</p>
+      <h3><a href="./input.txt">input.txt</a></h3>
+      <pre><code>{{ inputText }}</code></pre>
+      <h3><a href="./solution.js">solution.js</a></h3>
+      <pre><code>{{ solutionText }}</code></pre>
+    </div>
+    <script>
+const app = new Vue({
+  el: '#viewer',
+  data: () => {
+    return {
+      solutionText: '[Loading]',
+      inputText: '[Loading]'
+    }
+  },
+  computed: {
+    solutionTitle() {
+      const parts = (document.location + '').split('/')
+      return parts.reverse()[1]
+    }
+  },
+  async mounted () {
+    this.solutionText = (await axios.get('./solution.js')).data
+    this.inputText = (await axios.get('./input.txt')).data
+  }
+})
+    </script>
+  </body>
+</html>