反转字符串

import java.util.*;


public class Solution {
    /**
     * 反转字符串
     * @param str string字符串 
     * @return string字符串
     */
    public String solve (String str) {
        // write code here
        StringBuilder result = new StringBuilder();
        for (int i = str.length()-1 ; i >= 0 ; i--){
            result.append(str.charAt(i));
        }
        return result.toString();
    }
}