[BZOJ1800] [Ahoi2009] fly 飞行棋

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 int a[25][25];
 4 int main()
 5 {
 6     int n, ans = 0;
 7     cin >> n;
 8     for(int i = 1; i <= n; i++)
 9         cin >> a[i][i + 1];
10     a[n][1] = a[n][n + 1];
11     for(int i = 1; i <= n; i++)
12         for(int j = i + 2; j != i; j = j % n + 1)
13         {
14             if(j > n) j -= n;
15             if(j == 1) a[i][j] = a[i][n] + a[n][1];
16             else a[i][j] = a[i][j - 1] + a[j - 1][j];
17         }
18     for(int i = 1; i <= n; i++)
19         for(int j = i + 1; j <= n; j++)
20             for(int k = j + 1; k <= n; k++)
21                 for(int l = k + 1; l <= n; l++)
22                     if(a[i][j] == a[k][l] && a[j][k] == a[l][i])
23                         ans++;
24     cout << ans << endl;
25     return 0;
26 }