Problem 55
Description
This problem was asked by Microsoft.
Implement a URL shortener with the following methods:
shorten(url)
, which shortens the url into a six-character alphanumeric string, such aszLg6wl
.restore(short)
, which expands the shortened string into the original url. If no such shortened string exists, return null.
Hint: What if we enter the same URL twice?