Add solution #264

Author: JoshCrozier

solutions/0264-ugly-number-ii.js

@@ -0,0 +1,24 @@
+/**
+ * 264. Ugly Number II
+ * https://leetcode.com/problems/ugly-number-ii/
+ * Difficulty: Medium
+ *
+ * Write a program to find the n-th ugly number.
+ *
+ * Ugly numbers are positive numbers whose prime factors only include 2, 3, 5.
+ */
+
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var nthUglyNumber = function(n, factors = [2, 3, 5], offsets = [0, 0, 0]) {
+  const numbers = [1];
+  while (numbers.length < n) {
+    const candidates = factors.map((v, i) => numbers[offsets[i]] * v);
+    const target = Math.min(...candidates);
+    candidates.forEach((c, i) => target === c ? offsets[i]++ : null);
+    numbers.push(target)
+  }
+  return numbers[n - 1];
+};