Dictionary with Wildcard Search

Build a class PatternDictionary that stores words and checks patterns against them.

• addWord(word) stores word. Adding the same word twice is allowed and changes nothing.
• search(pattern) returns true if some stored word matches pattern, and false otherwise.

A word matches a pattern when they have the same length. Also, at each position, the pattern character must be either the same letter or a dot .. A dot matches exactly one letter, and it can be any letter. So ".at" matches "cat" and "bat", but not "at" or "cats".

Constraints:

• Words are 1 to 25 lowercase English letters. Patterns are 1 to 25 characters, each a lowercase letter or ..
• A pattern contains at most 3 dots.
• There can be up to 20,000 calls to addWord and 20,000 calls to search, in any order. A search only sees words added before it.