Write a function that takes a string as input and returns the string reversed.
Example:
Given s = "hello", return "olleh".
即反转字符串，逆序遍历依次append到StringBuffer即可
一刷：
public String reverseString(String s) {
StringBuffer sb=new StringBuffer();
for(int i=0;i<s.length();i++){
sb.append(s.charAt(s.length()-1-i));
}
return sb.toString();
}
原文：http://www.cnblogs.com/pulusite/p/5840452.html