hdu 1133(大数——Buy the Ticket)

题目大意:输入拥有50元的人数m和100元的人数n，求存在多少种情况使得能让这(n+m)个人都能顺利买到票(当存在100元的人买票时没钱找的话，即不成功)

解题思路：

package com.njupt.bigInteger;

import java.math.BigInteger;
import java.util.Scanner;

public class HDU_1133_1 {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		
		BigInteger m,n,c;
		BigInteger one = new BigInteger("1");
		int count = 1;
		while(scanner.hasNextInt()){
			c = one;
			int a = scanner.nextInt();
			int b = scanner.nextInt();
			
			if( a == 0 && b == 0){
				break;
			}else if( a < b){//一定要对这种情况进行处理,因为以下公式只是适用于a >= b的情况
				System.out.println("Test #"+count+++":");
				System.out.println("0");
				
			}else{
				int sum = a +b;
				m = new BigInteger(String.valueOf(a));
				n = new BigInteger(String.valueOf(b));
				
				
				for(int i = 1; i <= sum ; ++i){
					c = c.multiply(new BigInteger(String.valueOf(i)));
				}
				
				c = c.multiply(m.add(one).subtract(n)).divide(m.add(one));
				
				System.out.println("Test #"+count+++":");
				System.out.println(c);
			}
			
			
		}
	}
}