hdu 6025 card card card(双指针)

 1 #include<bits/stdc++.h>
 2 #define F(i,a,b) for(int i=a;i<=b;++i)
 3 using namespace std;
 4 
 5 const int N=2e6+7;
 6 int n,a[N],b[N],ans,ansval;
 7 
 8 int main(){
 9     while(~scanf("%d",&n))
10     {
11         F(i,1,n)scanf("%d",a+i),a[i+n]=a[i];
12         F(i,1,n)scanf("%d",b+i),b[i+n]=b[i];
13         ans=0,ansval=0,n*=2;
14         int l=1,sum=0,val=0;
15         F(r,1,n)
16         {
17             sum+=a[r]-b[r],val+=a[r];
18             if(val>ansval)ans=l-1,ansval=val;
19             while(sum<0||r-l+1>n)
20                 sum-=a[l]-b[l],val-=a[l],l++;
21         }
22         printf("%d\n",ans);
23     }
24     return 0;
25 }