Java|PAT|1005 Continue (3n+1) guess (25 points)|Analysis

The analytical answer is as follows:

import java.util.Arrays;
import java.util.Scanner;
/*
本题的关键：设置一个特大的数组，通过数组下标来记录所被覆盖的数！
如记录5这个数，就是在数组下标为5的位置上标记一下，
*/
public class Main {
    
    
    public static void main(String[] args) {
    
    
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[5000];
        int[] ioarr = new int[n];
        for (int i = 0; i < n; i++) {
    
    
            ioarr[i] = sc.nextInt();
        }
        int[] key = new int[n];
		//复制一下输入的数组
        for (int i = 0; i < n; i++) {
    
    
            key[i] = ioarr[i];
        }

        int[] ey = new int[n];

        for (int j = 0; j < n; j++) {
    
    
            while (ioarr[j]!=1){
    
    
            if (ioarr[j] % 2 == 0) {
    
    
                ioarr[j] = ioarr[j] / 2;

            } else {
    
    
                ioarr[j] = (3 * ioarr[j] + 1) / 2;

            }
            arr[ioarr[j]] = 1;}
        }
        for(int i=0;i<key.length;i++){
    
    
            if(arr[key[i]]!=1){
    
    
                ey[i]=key[i];
            }
        }

        Arrays.sort(ey);
        for(int i=ey.length-1;i>0;i--){
    
    
            if (ey[i]!=0&&ey[i-1]!=0){
    
    
                System.out.print(ey[i]+" ");
            }else if (ey[i]!=0&&ey[i-1]==0){
    
    
                System.out.print(ey[i]);
            }
        }

    }
}