#include<bits/stdc++.h>
using namespace std;
int a,b;
int main()
{
	freopen("a+b.in","r",stdin);
	freopen("a+b.out","w",stdout);
	cin>>a>>b;
	cout<<a+b;
	return 0;
}

首先，我们得认识freopen。 freopen("a.in","r",stdin);读入。 freopen("a.out","w",stdout);读出。(a为文件名） 接下来so-easy。

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int a,b;
	freopen("a+b.in","r",stdin);
	freopen("a+b.out","w",stdout);
	cin>>a>>b;
	cout<<a+b;
	return 0;
}

#include<iostream>
using namespace std;
int main(){
freopen("a+b.in","r",stdin);
freopen("a+b.out","w",stdout);
int a,b; cin>>a>>b; cout<<a+b;
return 0;
}

#include using namespace std; int main() { freopen("a+b.in","r",stdin); freopen("a+b.out","w",stdout); int a,b; cin>>a>>b; cout<<a+b; return 0; }