bzoj1800

简直暴力。。

#include <cstdio>int sum[30],n;int read_int () {char c = getchar();int re = 0;for(;c > '9' || c < '0';c = getchar());for(;c >= '0' && c <= '9';c = getchar())re = re * 10 + c - '0';return re;}int main () {n = read_int();for(int i = 1;i <= n;++i) {sum[i] += read_int();sum[i + 1] = sum[i];}int ans = 0;for(int i = 1;i <= n - 3;++i) {for(int j = i + 1;j <= n - 2;++j) {for(int k = j + 1;k <= n - 1;++k) {for(int l = k + 1;l <= n;++l) {int t1 = sum[j - 1] - sum[i - 1];int t2 = sum[l - 1] - sum[k - 1];int t3 = sum[k - 1] - sum[j - 1];int t4 = sum[n] - sum[l - 1] + sum[i - 1];if(t1 == t2 && t3 == t4)++ans;}}}}printf("%d\n",ans);}