UVA – 369 – Combinations

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        int n = in.nextInt(), r = in.nextInt();

        while ((n != 0 || r != 0)) {

            System.out.printf("%d things taken %d at a time 
 is %d exactly.\n",n,r,nCr(n,r))
                              ;

            n = in.nextInt();
            r = in.nextInt();
        }
    }

    private static long nCr(int n, int r) {

        if (n - r < r)
            r = n - r;

        double product = 1;
        for (int i = 1; i <= r; i++) {
            product = product * (n - r + i) / i;
        }

        return (long) product;
    }
}
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