leetcode[Reverse String]

解法一：

public class Solution {    public String reverseString(String s) {        StringBuilder sb = new StringBuilder(s);        sb = sb.reverse();        return sb.toString();    }}

解法二：

public class Solution {//递归做法public String reverseString(String s) {int length = s.length();if (length <= 1) return s;String leftStr = s.substring(0, length / 2);String rightStr = s.substring(length / 2, length);return reverseString(rightStr) + reverseString(leftStr);}}

解法三：

public class Solution {public String reverseString(String s) {char[] c = s.toCharArray();for(int i = 0, j = c.length - 1; i < j; i++, j--){//从首尾开始，交换char t = c[i];c[i] = c[j];c[j] = t;}return new String(c);}}