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.

丑数都是2，3，5的倍数，从1开始2，3，5得2，3，5，取其中最小值2再2，3，5得4，6，10。建一个PriorityQueue，把不重复的值存在queue中，每次剔除出最小值来2，3，*5，这样到第n个循环时候剔除出来的最小值就是第n个丑数。

class Solution {
    public int nthUglyNumber(int n) {
        PriorityQueue<Long> queue = new PriorityQueue<>();
        if(n == 1) return 1;
        long res = 1;
        queue.add(res);
        for(int i = 1; i <= n; i++) {
            res = queue.poll();
            if(!queue.contains(res * 2)) queue.add(res * 2);
            if(!queue.contains(res * 3)) queue.add(res * 3);
            if(!queue.contains(res * 5)) queue.add(res * 5);
        }
        return (int)res;
    }
}