BZOJ1800 [Ahoi2009]fly 飞行棋

//It is made by ljh2000
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
typedef long long LL;
const int MAXN = 45;
int n,a[MAXN],tot,sum,ans;
inline int getint(){
    int w=0,q=0; char c=getchar(); while((c<‘0‘||c>‘9‘) && c!=‘-‘) c=getchar();
    if(c==‘-‘) q=1,c=getchar(); while (c>=‘0‘&&c<=‘9‘) w=w*10+c-‘0‘,c=getchar(); return q?-w:w;
}

inline void work(){
	n=getint(); for(int i=1;i<=n;i++) a[i]=getint(),sum+=a[i];
	if(sum&1){ printf("0"); return ; } sum>>=1;
	for(int i=1,j=1;i<n;i++) {	tot+=a[i];	while(tot>sum) tot-=a[j++]; if(tot==sum) ans++; }
	printf("%d",ans*(ans-1)/2);
}

int main()
{
    work();
    return 0;
}