[JAVA/백준] 수학 3: 이항 계수 1

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import java.util.Scanner;
/**
 * @author HEESOO
 *
 */
public class Main {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner input=new Scanner(System.in);
		int n=input.nextInt();
		int k=input.nextInt();
		
		System.out.println(factorial(n)/(factorial(k)*factorial(n-k)));
	}
	public static int factorial(int x) {
		int answer=1;
		for(int i=x;i>0;i--) {
			answer*=i;
		}
		return answer;
	}
}