题解 | #字符串反转#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner fzhinput = new Scanner(System.in);
        String sr = fzhinput.nextLine();
        StringBuilder stack = new StringBuilder();
        int i;
        boolean pd = true;
        for(i=sr.length()-1; i>=0;i--){
            char c = sr.charAt(i);
            if(Character.isLowerCase(c)){
                pd = true;
            }
            else{
                System.out.println("只接受全是小写字母的字符串");
                pd = false;
                break;
            }
        }
        if( pd ){

            for(i=sr.length()-1; i>=0;i--){
            char c = sr.charAt(i);
                stack.append(c);           
            }

        }
        else{
            stack.setLength(0);
        }
        System.out.println(stack);


    
    }
}