public class Solution {
    public int nthSuperUglyNumber(int n, int[] primes) {
        //similar to ugly number 2, DP
        //d[i] = Math.min(min, d[i-1]*primes[j])
        //  example:   6 [2,3,7] 
        //2*[1,2,3,7],3*[1,2,3,7],7*[1,2,3,7] compare 2,3,7
        //[1,2]->2*[2,3,7],3*[1,2,3,7],7*[1,2,3,7] compare [4,3,7]
        //[1,2,3] -> 2*[2,3,7..],3*[2,3,7],7*[1,2,3,7...] compare[4,6,7] 
        //....
        //Time O(n*(primes.length))
    
        int[] d =new int[n];
        d[0]=1;
        int[] p = new int[primes.length];
        Arrays.fill(p,0);
        for(int i=1;i<n;i++){
            int min = Integer.MAX_VALUE;
            for(int j=0;j<primes.length;j++){
                min = Math.min(min,primes[j]*d[p[j]]) ;
            }
            d[i]=min;
            for(int k =0;k<primes.length;k++){
                if(min == primes[k]*d[p[k]]){
                    p[k]++;
                }
            }
        }
        return d[n-1];
    }
}

public class Solution {
    public int nthSuperUglyNumber(int n, int[] primes) {
        //similar to ugly number 2, DP
        //d[i] = Math.min(min, d[i-1]*primes[j])
        //  example:   6 [2,3,7] 
        //2*[1,2,3,7],3*[1,2,3,7],7*[1,2,3,7] compare 2,3,7
        //[1,2]->2*[2],3*[1,2],7*[1,2] compare [4,3,7]
        //....
        //Time O(n*(primes.length))
    
        int[] d =new int[n];
        d[0]=1;
        int[] p = new int[primes.length];
        Arrays.fill(p,0);
        for(int i=1;i<n;i++){
            int min = Integer.MAX_VALUE;
            for(int j=0;j<primes.length;j++){
                min = Math.min(min,primes[j]*d[p[j]]) ;
            }
            d[i]=min;
            for(int k =0;k<primes.length;k++){
                if(min == primes[k]*d[p[k]]){
                    p[k]++;
                }
            }
        }
        return d[n-1];
    }
}

Update SuperUglyNumber.java