leetcode 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.

#include "stdafx.h"
#include<vector>
#include<iostream>
using namespace std;

class Solution {  
public:  
	bool is_ugly(int num,vector<int> primes)  
	{  
		int k=0;  
		while(k!=primes.size())  
		{  
			while(num%primes[k]==0)  
			{  
				num/=primes[k];  
			}  
			k++;  
			if(num==1)  
				return true;  
		}  
		return false;  
	}  
	int findnext(int tt,vector<int> primes,bool f)  
	{  
		bool flag=false;  
		if(!f)
			while(!flag)  
			{  
				++tt;
				flag=is_ugly(++tt,primes);  
			}  
		else
			while(!flag)  
			{  
				flag=is_ugly(++tt,primes);  
			}  
			return tt;  
	}  
	int nthSuperUglyNumber(int n, vector<int>& primes)  
	{  
		if(n==1)  
			return 1;  
		if(n==2)  
			return primes[0]==1?primes[1]:primes[0];  
		vector<int>nums;  
		nums.push_back(1);  
		int k=1;
		bool f=false;
		if(primes[0]==2)
			f=true;
		while(k!=n)  
		{  
			nums.push_back(findnext(nums.back(),primes,f));  
			k++;  
		}  
		return nums.back();  
	}  
};  
int _tmain(int argc, _TCHAR* argv[])
{
	Solution sl;
	int aa[30]={7,19,29,37,41,47,53,59,61,79,83,89,101,103,109,127,
		131,137,139,157,167,179,181,199,211,229,233,239,241,251};
	vector<int>primes(aa,aa+30);
	cout<<sl.nthSuperUglyNumber(100000,primes);

	system("pause");
	return 0;
}

Time Limit Exceeded