UVa:369 Combinations

最新推荐文章于 2020-01-13 16:38:37 发布

原创最新推荐文章于 2020-01-13 16:38:37 发布 · 924 阅读

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#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<algorithm>
using namespace std;
long long C(int n,int k)
{
     long double s=1.0;
     for(long double i=0.0;i<k;++i)
     {
        s*=(n-i)/(k-i);
     }
     return (long long)(s+0.5);
}
int main()
{
   //freopen("in.txt","r",stdin);
    int M,N;
    while(scanf("%d%d",&M,&N)==2&&!(!M&&!N))
    {
     printf("%d things taken %d at a time is %lld exactly.\n",M,N,C(M,N));
    }
    return 0;
}