LeetCode 472 | Concatenated Words | HashSet | Recursion | Java

[sleepycracker]

For the time and space complexity,
Space is O(n) for each string in the set
Time is O(n) for function, but inside this function has a helper to call it recursively
the worst case for helper function is O(k^2) where k is the length of the word because it could keep calling every single character when it almost match but it actually didn't match!
Therefore the totally time complexity is O(n*k^2)