• Source 
    1. #include <iostream>
    2. #include <vector>
    3. using namespace std;
    4. const int N=1000000;
    5. bool mark[N+1000];
    6. int main()
    7. {
    8. 	vector<int> primes;
    9. 	vector<long long> sum;
    10. 	for(int i=2;i<=N/2;++i)
    11. 		if(mark[i]==false)
    12. 		{
    13. 			int b=i+i;
    14. 			while(b<=N)
    15. 			{
    16. 				mark[b]=true;
    17. 				b+=i;
    18. 			}
    19. 		}
    20. 	primes.push_back(2);
    21. 	sum.push_back(2);
    22. 	for(int i=3;i<=N;++i)
    23. 		if(mark[i]==false)
    24. 		{
    25. 			primes.push_back(i);
    26. 			sum.push_back( sum[sum.size()-1]+i);
    27. 		}
    28. 	int t;
    29. 	cin>>t;
    30. 	primes.push_back(10000000);
    31. 	for(int k=1;k<=t;++k)
    32. 	{
    33. 		int n;
    34. 		cin>>n;
    35. 		int i;
    36. 		for(i=0;primes[i]<=n;++i);
    37. 		cout<<sum[i-1]<<endl;
    38. 	}
    39.  
    40. }