void reverse(char *str)

#include <iostream>
using namespace std;

//this method complexity is  O(n) time and O(1) space 
void reverse(char *str) {
    cout<<str<<endl;
    char *end=str;
    while(*end)
        end++;
    end--;
    char *start = str;
    while (start<end){
        char temp = *start;
        *start++ = *end;
        *end-- = temp;
    }
    cout <<str<<endl;
        
}

int main(int argc, const char * argv[])
{
    char test[] = "My startup kills";
    char *pointer = test;
    //pointer++;
    //*pointer = 'a';
    reverse(pointer);   
}