P1304 哥德巴赫猜想 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

#include<bits/stdc++.h>
using namespace std;
struct student
{string name;int c,m,e,s;	
};
bool check(int n)
{for(int i=2;i*i<=n;i++){if(n%i==0)return 0;}return 1;
}
void out(int n)
{for(int i=2;i<=n;i++){if(check(i)&&check(n-i)){cout<<n<<'='<<i<<'+'<<n-i<<endl;break;}}
}
int main()
{int n;cin>>n;int cnt=0;for(int i=4;i<=n;i+=2){out(i);}return 0;
}