Strings — Reverse Words in a String

solve(s) — a word is a run of non-space characters. Return the words of s in
reverse order, joined by a single space, with no leading or trailing spaces. The
input may contain leading, trailing or repeated spaces, which must not appear in the
output. A string with no words returns "".

The interview follow-up is to do it in place on a character array: reverse the whole
string, then reverse each word back. Here, any correct approach is accepted — but be able to
explain both.

Examples

solve("the sky is blue")      → "blue is sky the"
solve("  hello world  ")      → "world hello"
solve("a good   example")     → "example good a"