Write a function that takes a string as input and returns the string reversed.

Example:
Given s = “hello”, return “olleh”.

这道题没什么难度，直接从两头往中间走，同时交换两边的字符即可，参见代码如下：

解法一：

class Solution {
public:
    string reverseString(string s) {
        int left = 0, right = s.size() - 1;
        while (left < right) {
            char t = s[left];
            s[left++] = s[right];
            s[right--] = t;
        }
        return s;
    }
};

我们也可以用swap函数来帮助我们翻转：

解法二：

class Solution {
public:
    string reverseString(string s) {
        int left = 0, right = s.size() - 1;
        while (left < right) {
            swap(s[left++], s[right--]);
        }
        return s;
    }
};

类似题目：

Reverse Words in a String II

Reverse Words in a String