1586=计算组合数-java代码

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        for (int i = 1; i <= n; i++) {
            int a = scanner.nextInt();
            int b = scanner.nextInt();
            System.out.println(dg(a, b));
        }
    }

    public static int dg(int a, int b) {
        if (b == 0)
            return 1;
        else if (a == 1)
            return 1;
        else if (a == b)
            return 1;
        else
            return dg(a-1,b-1)+dg(a-1,b);
    }
}