>  1 #include<iostream>
>  2 #include<algorithm>
>  3 using namespace std;
>  4 const int maxn=110;
>  5 int n;
>  6 int ans;
>  7 int totalS,totalF;
>  8 struct node
>  9 {
> 10     int s,f;
> 11 }a[maxn];
> 12 int sum[maxn];
> 13 void dfs(int cnt)
> 14 {
> 15     if(cnt==n)
> 16     {
> 17         if(totalS>=0 && totalF>=0)
> 18             ans=max(totalS+totalF,ans);
> 19         return;
> 20     }
> 21     if(a[cnt].s+a[cnt].f<0 && totalS+totalF<ans) return;
> 22     if(totalS+totalF+sum[cnt]<=ans) return;
> 23 
> 24     totalS+=a[cnt].s;
> 25     totalF+=a[cnt].f;
> 26     dfs(cnt+1);
> 27 
> 28     totalS-=a[cnt].s;
> 29     totalF-=a[cnt].f;
> 30     dfs(cnt+1);
> 31 }
> 32 bool cmp(const node & n1,const node& n2)
> 33 {
> 34     return n1.s+n1.f>n2.s+n2.f;
> 35 }
> 36 int main()
> 37 {
> 38     scanf("%d",&n);
> 39     totalS=totalF=0;
> 40     ans=0;
> 41     for(int i=0;i<n;i++)
> 42     {
> 43         scanf("%d%d",&a[i].s,&a[i].f);
> 44         if(a[i].s>=0 && a[i].f>=0)
> 45         {
> 46             totalS+=a[i].s;
> 47             totalF+=a[i].f;
> 48             i--;
> 49             n--;
> 50         }
> 51         else if(a[i].s<0 && a[i].f<0)
> 52         {
> 53             i--;
> 54             n--;
> 55             continue;
> 56         }
> 57     }
> 58     ans=totalS+totalF;
> 59     sort(a,a+n,cmp);
> 60     memset(sum,0,sizeof(sum));
> 61     for(int i=n-1;i>=0;i--)
> 62     {
> 63         if(a[i].s+a[i].f<=0) sum[i]=0;
> 64         else sum[i]=sum[i+1]+a[i].s+a[i].f;
> 65     }
> 66     dfs(0);
> 67     cout<<ans<<endl;
> 68 }