一個簡單的小工具-計算組合數-C++/C

計算C(n,m)

int c(int m,int n){
    	if(n<=m) return 1;
    	if(m>=n/2){m = n-m;}
    	double t_m = m,t_n = n;
    	double a=1,b=1;
    	for (int i = 0; i < m; ++i)
    	{
    		a *= t_m--;
    		b *= t_n--;
    	}
    	return (int) (b/a+0.5);
    }