UVa 369 – Combinations

　　题目大意：给两个数n, m，求C(n, m)。用java直接写就好了。

 import java.io.*;
 import java.util.*;
 import java.math.*; class Main
 {
     public static void main(String[] args)
     {
         Scanner sc = new Scanner(System.in);
         BigInteger[] fact = new BigInteger[110];
         fact[0] = BigInteger.ONE;
         for (int i = 1; i <= 100; i++)
             fact[i] = fact[i-1].multiply(BigInteger.valueOf(i));
         int n, m;
         while (sc.hasNext())
         {
             n = sc.nextInt();
             m = sc.nextInt();
             if (n == 0 && m == 0)  break;
             BigInteger ans = fact[n].divide(fact[m]).divide(fact[n-m]);
             System.out.println(n + " things taken " + m + " at a time is " + ans + " exactly.");
         }     }
 }