题解 | #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
        //方法一：首位交换，时间复杂度为：O(n/2)，空间复杂度为：O(1)
        int length = str.length();
        if(length == 0){
            return "";
        }
        
        char[] cha = str.toCharArray();
        char temp;
        int len = length/2;
        for(int i=0;i<len;i++){
            temp = cha[i];
            cha[i] = cha[length-1-i];
            cha[length-1-i] = temp;
        }
        String s = new String(cha);
        return s;
        
        //方法二：使用对象StringBuffer，调用reverse函数
//         StringBuffer stringBuffer = new StringBuffer(str);
//         return stringBuffer.reverse().toString();
    }
}