1 import java.util.*; 2  import java.math.*; 3  public class Main 4  { 5      public static void main(String []args) 6      { 7          Scanner cin=new Scanner(System.in); 8          int i,n,m; 9          int count=1;10          while(cin.hasNext())11          {    12              m=cin.nextInt();13              n=cin.nextInt();14              BigInteger s1 = BigInteger.valueOf(1);15              BigInteger s2 = BigInteger.valueOf(1);16              BigInteger s3 = BigInteger.valueOf(1);17              for(i=1;i<=n+m;i++)18              {19                  s1=s1.multiply(BigInteger.valueOf(i));20              }21              for(i=1;i<=n;i++)22              {23                   s2=s2.multiply(BigInteger.valueOf(i));24              }25              for(i=1;i<=m;i++)26              {27                   s3=s3.multiply(BigInteger.valueOf(i));28              }29              s2=s2.multiply(s3);30              s1=s1.multiply(BigInteger.valueOf(m+1-n));31              s1=s1.divide(BigInteger.valueOf(m+1));32              System.out.println(s1.divide(s2));    33          }34      }35  }

这个题目和

Buy the Ticket非常相似，具体解释见

Buy the Ticket的解释，只是这里不需要对m 和n进行全排列