#include<iostream> #include<cstring> #include<string> using namespace std; const int SIZE = 10000; const int LENGTH = 10; int n, m, a[SIZE][LENGTH]; int h(int u, int v) { int ans, i; ans = 0; for (i = 1; i <= n; i++) if (a[u][i] != a[v][i]) ans++; return ans; } int main( ) { int sum, i, j; cin >> n; memset(a, 0, sizeof(a)); m = 1; while (1) { i = 1; while ((i <= n) && (a[m][i] == 1)) i++; if (i > n) break; m++; a[m][i] = 1; for (j = i + 1; j <= n; j++) a[m][j] = a[m - 1][j]; } sum = 0; for (i = 1; i <= m; i++) for (j = 1; j <= m; j++) sum += h(i, j); cout << sum << endl; return 0; }
输入:7
输出:1