Given an input string, reverse the string word by word.
s = "the sky is blue",
"blue is sky the".
- What constitutes a word?
A sequence of non-space characters constitutes a word.
- Could the input string contain leading or trailing spaces?
Yes. However, your reversed string should not contain leading or trailing spaces.
- How about multiple spaces between two words?
Reduce them to a single space in the reversed string.