313. Super Ugly Number

Write a program to find the nth super ugly number.

Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k. For example, [1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32] is the sequence of the first 12 super ugly numbers given primes = [2, 7, 13, 19] of size 4.

Note: (1) 1 is a super ugly number for any given primes. (2) The given numbers in primes are in ascending order. (3) 0 < k ≤ 100, 0 < n ≤ 106, 0 < primes[i] < 1000.

public class Solution {
    public int nthSuperUglyNumber(int n, int[] primes) {

        List<Integer> res = new ArrayList<>();
        res.add(1);
        int[] index = new int[primes.length];
        for(int i=0;i<index.length;i++) index[i] = 0;

        while(true){
            if(res.size() == n) return res.get(res.size()-1);
            int tmp = Integer.MAX_VALUE;
            int smallestIndex = -1;
            for(int i=0; i< index.length;i++){
                int t = res.get(index[i])*primes[i];
                if(t < tmp){
                    tmp = t;
                    smallestIndex = i;
                }
            }
            index[smallestIndex]++;
            if(res.get(res.size()-1) != tmp)
                res.add(tmp);

        }

    }
}

another method is to use PriorityQueue

to be finished