蓝桥杯算法提高VIP-素数求和 (C++代码实现)

参考代码:

#include<iostream>

#include<cmath>

using namespace std;

int a[2000010];

int main(){

             long long sum=0;

             int n;

             cin>>n; 

             //用埃氏筛选法选出前n个数是素数的数 

             for(int i=2;i<=sqrt(n);i++){

                     for(int j=i*i;j<=n;j+=i){

                              //将数组下标不是素数的元素赋值为1 

                             a[j]=1;

                     }

             }

             //累计求和 

             for(int i=2;i<=n;i++){

                     if(a[i]==0){

                             sum+=i;       

                     }

             }

             cout<<sum<<endl;

             return 0;

}