Reverse String.cpp

/*
Reverse String
==============

Write a function that reverses a string. The input string is given as an array of characters char[].

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of printable ascii characters.


Example 1:
Input: ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]

Example 2:
Input: ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]

Hint #1  
The entire logic for reversing a string is based on using the opposite directional two-pointer approach!

*/

class Solution
{
public:
  void reverseString(vector<char> &s)
  {
    int f = 0, b = s.size() - 1;
    while (f < b)
    {
      char ch = s[f];
      s[f] = s[b];
      s[b] = ch;
      f++;
      b--;
    }
  }
};