Write a function that takes a string as input and returns the string reversed.
Example:
Given s = "hello", return "olleh".
思路：字符串反转，交换s[i]和s[s.size()-1-i]
代码：
1 class Solution { 2 public: 3 string reverseString(string s) { 4 int i=0,j=s.size()-1; 5 while(i<j){ 6 swap(s[i++],s[j--]); 7 } 8 return s; 9 } 10 };
原文：http://www.cnblogs.com/Deribs4/p/5693772.html