bzoj1800

题解：

暴力枚举，然后判断是否是矩形

代码：

#include<iostream>
#include<cstdio>
using namespace std;
int n,ans,tot,a[],dis[];
int read()
{
    char ch=getchar();
    int f=,x=;
    while(!(ch>=''&&ch<='')){if(ch=='-')f=-;ch=getchar();}
    while(ch>=''&&ch<=''){x=x*+(ch-'');ch=getchar();}
    return x*f;
}
int main()
{
    n=read();
    for (int i=;i<=n;i++)a[i]=read();
    for (int i=;i<=n;i++)
      {
        dis[i+]=dis[i]+a[i];
        tot+=a[i];
     }
    for (int a=;a<=n;a++)
     for (int b=a+;b<=n;b++)
      for (int c=b+;c<=n;c++)
       for (int d=c+;d<=n;d++)
        if((dis[b]-dis[a]==dis[d]-dis[c])
        &&(tot-dis[d]+dis[a]==dis[c]-dis[b]))ans++;
    printf("%d",ans);
    return ;
}