灵活运用String.split/replaceAll的正则表达式用法

import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner scan=new Scanner(System.in);
        String input=scan.nextLine();
        input=input.replaceAll("[^a-zA-Z]"," ");
        String[] outputs=input.split("\\s+");
        for(int i=outputs.length-1;i>=0;i--){
            System.out.print(outputs[i]+" ");
        }
    }
}