1、题目：
Write a function that takes a string as input and returns the string reversed.
Example:
Given s = "hello", return "olleh".
2、代码实现：
代码实现1:
public static String reverseString(String s) { if (s == null) { return null; } if (s.length() == 0) { return ""; } int length = s.length(); char[] chars = s.toCharArray(); String result = ""; for (int i = chars.length - 1; i >=0; --i) { result += chars[i]; } return result; }
代码实现2:
public String reverseString(String s) { return new StringBuffer(s).reverse().toString(); }
