Ugly Number II
Write a program to find the n -th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5 . Example: Input: n = 10 Output: 12 Explanation: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 10 ugly numbers. Note: 1 is typically treated as an ugly number. n does not exceed 1690 . class Solution { public int nthUglyNumber(int n) { int[] ugly = new int[n]; ugly[0] = 1; int indexOf2 = 0, indexOf3 = 0, indexOf5 = 0; int factorOf2 = 2, factorOf3 = 3, factorOf5 = 5; for(int i=1;i<n;i++){ int min = Math.min(Math.min(factorOf2,factorOf3),factorOf5); ugly[i] = min; if(factorOf2 == min) factorOf2 = 2*ugly[++indexOf2]; if(factorOf3 == min) factorOf3 = 3*ugly[++indexOf3]; if(factorOf5 == min) factorOf5 = 5*ugly[++