题目：

题解：

class Solution {
public:int nthUglyNumber(int n) {vector<int> dp(n + 1);dp[1] = 1;int p2 = 1, p3 = 1, p5 = 1;for (int i = 2; i <= n; i++) {int num2 = dp[p2] * 2, num3 = dp[p3] * 3, num5 = dp[p5] * 5;dp[i] = min(min(num2, num3), num5);if (dp[i] == num2) {p2++;}if (dp[i] == num3) {p3++;}if (dp[i] == num5) {p5++;}}return dp[n];}
};