leetcode---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.
(4) The nth super ugly number is guaranteed to fit in a 32-bit signed integer.

class Solution {public:    int nthSuperUglyNumber(int n, vector<int>& primes)     {        int m = primes.size();        vector<int> dp(n, 1);        vector<int> index(m, 0);        for(int i=1; i<n; i++)        {            dp[i] = INT_MAX;            for(int j=0; j<m; j++)                dp[i] = min(dp[i], dp[index[j]] * primes[j]);            for(int j=0; j<m; j++)                if(dp[i] == dp[index[j]] * primes[j])                    index[j]++;        }        return dp[n-1];    }};