1586=计算组合数-java代码

 1 import java.util.Scanner;
 2 
 3 public class Main {
 4 
 5     public static void main(String[] args) {
 6         Scanner scanner = new Scanner(System.in);
 7         int n = scanner.nextInt();
 8         for (int i = 1; i <= n; i++) {
 9             int a = scanner.nextInt();
10             int b = scanner.nextInt();
11             System.out.println(dg(a, b));
12         }
13     }
14 
15     public static int dg(int a, int b) {
16         if (b == 0)
17             return 1;
18         else if (a == 1)
19             return 1;
20         else if (a == b)
21             return 1;
22         else
23             return dg(a-1,b-1)+dg(a-1,b);
24     }
25 }