[NowCoder]字符逆序

import java.util.*;
public class Main2 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        while(sc.hasNext())
        {
            String str = sc.nextLine();
            
            StringBuilder sb = new StringBuilder();
            for(int i = str.length()-1; i >= 0; i--)
            {
                char ch = str.charAt(i);
                sb.append(ch);
            }
            System.out.println(sb.toString());
        }

    }
}

import java.util.*;

public class Main {
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        
        while(scan.hasNext())
        {
            String str = scan.nextLine();
            
            Stack stack = new Stack();
            
            for(char ch : str.toCharArray())
            {
                stack.push(ch);
            }
            
            while(!stack.empty())
            {
                System.out.print(stack.pop());
            }
        }
    }
}

import java.util.*;

public class Main3 {

    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        
        while(sc.hasNext())
        {            
            String str = sc.nextLine();
            
            StringBuilder sb = new StringBuilder(str);
            
            System.out.println(sb.reverse().toString());            
        }
    }
}