递归的几个经典例子

注意:构造方法不可递归,否则是无限创建对象;

递归的几个经典例子:
1.HannoiTower

import java.util.Scanner;
 public class HanoiTower{
     //level代表盘子个数;三个char类型代表柱子
    public static void moveDish(int level, char from, char inter, char to){
         if(level == 1){
             System.out.println("从"+from+"移动盘子1号到"+to);
         }else{

             moveDish(level-1,from,to,inter);//调用自身
            System.out.println("从"+from+"移动盘子"+level+"号到"+to);
             moveDish(level-1,inter,from,to);
         }
     }

    public static void main(String[] args){
         Scanner sc = new Scanner(System.in);
         System.out.println("请输入盘子个数");
         int n = sc.nextInt();
         moveDish(n,'a','b','c');
     }
 }

2.sum

import java.util.Scanner;
 public class Sum{
     public static void main(String[] args){
         Scanner sc = new Scanner(System.in);
         System.out.println("请输入n:");
         int n = sc.nextInt();
         int sum1 = sum(n);
        System.out.println(sum1;
     }

    public static int sum(int n){
         if(n == 1){
             return 1;
         }else{
             return n+sum(n-1);
         }
     }
 }

3.factorial

import java.util.Scanner;
 public class Factorial{
     public static void main(String[] args){
         Scanner sc = new Scanner(System.in);
         System.out.println("请输入一个小于20的整数,我会帮你求出它的阶乘:");
         int n = sc.nextInt();
         int fac1 = fac(n);
         System.out.println(n+"的阶乘为:"+fac1);
         System.out.println("~看我棒不棒~~");
     }

    public static int fac(int n){
         if(n == 1){B
             return 1;
         }else{
             return n*fac(n-1);
         }
     }
 }

4.sumFactorial

import java.util.Scanner;
 public class SumFactorial{
     public static void main(String[] args){
         Scanner sc = new Scanner(System.in);
         System.out.println("请输入一个小于20的整数:");
         int n = sc.nextInt();
         int sf = sumFac(n);
         System.out.println(sf);
     }
     //阶乘和的累加
    public static int sumFac(int n){
         if(n == 1){
             return 1;
         }else{
             return fac(n)+sumFac(n-1);
         }
     }
     //求阶乘
    public static int fac(int n){
         if(n == 1){
             return 1;
         }else{
             return n*fac(n-1);
         }
     }
 }

5.使用递归，遍历 1 至100之间的每个数字

public class Number{
     public static void main(String[] args){
         iterator(100);
     }

    public static void iterator(int n){
         if(n >= 1){
             System.out.print(n+"	");
             n--;
             iterator(n);
         }

    }
 }