经典递归问题（二）角谷定理（Java）

//递归
import java.util.Calendar;
import java.util.Scanner;
public class Test02 {
	public static int step=0;
	public static void main(String[] args) {
		System.out.println("请输入一个数");
		Scanner scanner = new Scanner(System.in);
		int m=scanner.nextInt();
		cal(m);
		System.out.print("\n");
		System.out.println("step="+step);
	}
	public static int cal(int m) {
		if((m%2==1)&&m!=1) {//为奇数
			step++;
			m=3*m+1;
			System.out.print(m+" ");
			m=cal(m); //继续计算
			return m;
		}
		else if(m%2==0) {//m为偶数
			step++;
			m=m/2; //除以二
			System.out.print(m+" ");
			m=cal(m);//继续计算
			return m;
		}
		else if(m==1) {
			step++;
		}
			return m;	
	}
}

//（非递归）：
import java.util.Scanner;
public class Test2_2 {
	public static void main(String[] args) {
		int step=0;
		System.out.print("输入");
		Scanner scanner = new Scanner(System.in);
		int m=scanner.nextInt();
		if(m<0){
			System.out.println("非法输入");
			return;
		}
		while(m!=1)
		{
			if(m%2==1){
				step++;
				m=3*m+1;
				System.out.print(m+" ");
			}else {
				step++;
				m=m/2;
				System.out.print(m+" ");
			}
		}
		System.out.print("\n");
		System.out.println("step="+step);
	}
}