#include<bits/stdc++.h> using namespace std; int n; char a, b, c; void f(int n, char a, char b, char c) { if (n == 1) { cout << a << "->" << n << "->" << b << endl; return; } f(n - 1, a, c, b); //将n-1个盘子从a移动到c(借助b) cout << a << "->" << n << "->" << b << endl; f(n - 1, c, b, a); //将n-1个盘子从c移动到b(借助a) } int main() { cin >> n >> a >> b >> c; //将n个盘子从a移动到b（借助c） f(n, a, b, c); return 0; }

快谢谢我俩

#include <bits/stdc++.h> using namespace std; int main() { int n; cin >> n; long long o= (n + 1) / 2;
long long e = n / 2;
long long t = (long long)n * n; long long o_p = o * o; long long e_p= t - o_p; long long d_e = e; long long a = d_e + (e_p - d_e) / 2;

cout << a << endl;
return 0;

}

#include using namespace std;

int main() { int n; cin >> n; int ans = 0; for (int a = 1; a <= n; ++a) { for (int b = a; b <= n; ++b) { if ((1LL * a * b) % 2 == 0) { ans++; } } } cout << ans << endl; return 0; }