Calling methods from within other methods
------------------------程序如下:-----------------------------
/*
* File: Combinations.java
* -----------------------
* This program computes the mathematical combinations function
* C(n, k), which is the number of ways of selecting k objects
* from a set of n distinct objects.
*/
package chapter5;
import java.util.Scanner;
public class Combinations {
public void run(){
int n;
int k;
int result;
System.out.println("please input the n:");
Scanner input=new Scanner(System.in);
n=input.nextInt();
System.out.println("please input the k:");
Scanner input1=new Scanner(System.in);
k=input1.nextInt();
result=Combinations(n,k); // 调用函数Combinations(int n,int k)
System.out.println("C("+n+","+k+")="+result);
}
// 计算C(n,k)=n!/(k!*(n-k)!)
private static int Combinations(int n,int k){
int result;
result=factorial(n)/(factorial(k)*factorial(n-k)); // 调用函数factorial(int n)
return result;
}
// 计算n!
private static int factorial(int n) {
int result=1;
for(int i=1;i<=n;i++){
result*=i;
}
return result;
}
}
-------------------------运行程序-----------------
