344-Reverse-String.cpp

class Solution {
public:
    void swap (char &a, char &b) {
        char temp = a;
        a = b;
        b = temp;
    }
    void reverseString(vector<char>& s) {
        int i = 0, j = s.size() - 1;

        while (i < j) {
            swap(s[i++], s[j--]);
        }
    }
};