代码已更改
```cpp
#include<bits/stdc++.h>
#define int long long
using namespace std;
struct data{
int s,f;
}cow[405];
int n,ans;
bool vis[1005];
void dfs(int s,int f,int c,int i){
if(c>n)return;
if(s>=0&&f>=0)ans=(s+f)>ans?(s+f):ans;
if(!(cow[i].s<=0&&cow[i].f<=0))dfs(s+cow[i].s,f+cow[i].f,c+1,i+1);
if(!(cow[i].s>0&&cow[i].f>0))dfs(s,f,c+1,i+1);
}
signed main(){
// freopen(".in","r",stdin);
// freopen(".out","w",stdout);
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
cin>>n;
for(int i=1;i<=n;++i){
cin>>cow[i].s;
cin>>cow[i].f;
}
dfs(0,0,0,1);
cout<<ans;
return 0;
}
/*
5
-5 7
8 -6
6 -3
2 1
-8 -5
*/
```
by wsdyz2010 @ 2023-09-22 14:30:21
63pts，TLE on 2 7 10 11
by wsdyz2010 @ 2023-09-22 14:31:25