Write a function that reverses a string. The input string is given as an array of characters s.
Space: O(1)
Time: O(n)
*/
void reverseString(char* s, int sSize){
int h = sSize/2;
for (int i=0; i<h; i++) {
char tmp = s[i];
s[i] = s[sSize-i-1];
s[sSize-i-1] = tmp;
}
}