Leetcode: Reverse String

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

Example:
Given s = "hello", return "olleh".

这个题目比较straightforward，因为我们可以从这个string的首尾开始swap，直到相遇

class Solution {
public:
    string reverseString(string s) {
        if (s.size() <= 1) {
            return s;
        }
        for (int i=0, j=s.size()-1; i<j; ++i, --j) {
            char temp = s[i];
            s[i] = s[j];
            s[j] = temp;
        }
        return s;
    }
};