#include <iostream>
using namespace std;
typedef long long ll;
ll C(ll n, ll m)
{
ll res = 1;
for(ll i = 1; i <= m; ++i)
res = res*(n-m+i)/i;
return res;
}
int main()
{
cout << C(100,15) << endl;
return 0;
}
参考:http://blog.youkuaiyun.com/perfumekristy/article/details/8713083