algorithm - Reverse the ordering of words in a string

Question

I have this string s1 = "My name is X Y Z" and I want to reverse the order of the words so that s1 = "Z Y X is name My".

I can do it using an additional array. I thought hard but is it possible to do it inplace (without using additional data structures) and with the time complexity being O(n)?

Answer 1

Reverse the entire string, then reverse the letters of each individual word.

After the first pass the string will be

s1 = "Z Y X si eman yM"

and after the second pass it will be

s1 = "Z Y X is name My"