2024 day 11 in javascript

2024/11/solution.js

@@ -0,0 +1,42 @@
+
+const input = (await Bun.file(Bun.argv[2]).text()).trim()
+const stones = input.split(" ").map(num => parseInt(num))
+
+const splits = num => countDigits(num) % 2 == 0;
+
+const countDigits = num => Math.floor(Math.log10(num)) + 1;
+
+const getLeft = num => Math.floor(num / Math.pow(10, countDigits(num) / 2));
+const getRight = num => num - getLeft(num) * Math.pow(10, countDigits(num) / 2);
+
+const memo = new Map();
+
+const blinkTimes = (times, num) => {
+  if (times == 0) return 1;
+  const key = times + '*' + num;
+  if (memo.has(key)) {
+    return memo.get(key)
+  }
+  let result
+  if (num === 0) {
+    result = blinkTimes(times-1, 1)
+  } else if (splits(num)) {
+    result = blinkTimes(times-1, getLeft(num)) + blinkTimes(times-1, getRight(num))
+  } else {
+    result = blinkTimes(times-1, num * 2024)
+  }
+  memo.set(key, result)
+  return result;
+}
+
+let count = 0
+for (const stone of stones) {
+  count += blinkTimes(25, stone)
+}
+console.log("part 1", count)
+
+count = 0
+for (const stone of stones) {
+  count += blinkTimes(75, stone)
+}
+console.log("part 2", count)