BZOJ——T 1800: [Ahoi2009]fly 飞行棋

 1 #include <cstdlib>
 2 #include <cstdio>
 3 
 4 inline void read(int &x)
 5 {
 6     x=0; register char ch=getchar();
 7     for(; ch>‘9‘||ch<‘0‘; ) ch=getchar();
 8     for(; ch>=‘0‘&&ch<=‘9‘; ch=getchar()) x=x*10+ch-‘0‘;
 9 }
10 const int N(110);
11 int n,len,cnt,pos[N],ii[N],vis[N*1000];
12 
13 int Presist()
14 {
15 //    freopen("A.in","r",stdin);
16 //    freopen("A.out","w",stdout);
17     
18     read(n); pos[1]=0; vis[0]=1;
19     for(int i=1; i<=n; ++i)
20     {
21         read(ii[i]),len+=ii[i];
22         pos[i+1]=pos[i]+ii[i];
23         vis[pos[i+1]]=i+1;
24     }    len>>=1;
25     for(int i=1; i<=n&&pos[i]<=len; ++i)
26         if(vis[pos[i]+len]<=n&&vis[pos[i]+len]) ++cnt;
27     printf("%d",cnt*(cnt-1)/2);
28     return 0;
29 }
30 
31 int Aptal=Presist();
32 int main(){;}