Reverse String | LeetCode

 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"]

Solution:

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