Update 264-ugly-number-ii.js

Author: everthis

264-ugly-number-ii.js

@@ -2,15 +2,19 @@
  * @param {number} n
  * @return {number}
  */
-const nthUglyNumber = function(n) {
-  const dp = [1]
-  let [a, b, c] = [0, 0, 0]
+const nthUglyNumber = function (n) {
+  if (n <= 0) return false
+  if (n === 1) return true
+  let t2 = 0,
+    t3 = 0,
+    t5 = 0
+  const k = Array(n).fill(1)
+  k[0] = 1
   for (let i = 1; i < n; i++) {
-    let [ua, ub, uc] = [dp[a] * 2, dp[b] * 3, dp[c] * 5]
-    dp[i] = Math.min(ua, ub, uc)
-    if (dp[i] === ua) a++
-    if (dp[i] === ub) b++
-    if (dp[i] === uc) c++
+    k[i] = Math.min(k[t2] * 2, k[t3] * 3, k[t5] * 5)
+    if (k[i] == k[t2] * 2) t2++
+    if (k[i] == k[t3] * 3) t3++
+    if (k[i] == k[t5] * 5) t5++
   }
-  return dp[n - 1]
+  return k[n - 1]
 }