[LeetCode] 290. Word Pattern

 Problem : https://leetcode.com/problems/word-pattern/

Use 2 hash maps to save the mapping relationship.

class Solution:
    def wordPattern(self, pattern: str, str: str) -> bool:
        word = str.split(' ')
        
        w2p = defaultdict(lambda : '')
        p2w = defaultdict(lambda : '')
        
        if len(word) != len(pattern):
            return False
        
        for i in range(len(pattern)):
            if pattern[i] not in p2w and word[i] not in w2p:
                p2w[pattern[i]] = word[i]
                w2p[word[i]] = pattern[i]
            
            elif p2w[pattern[i]] != word[i] or w2p[word[i]] != pattern[i]:
                return False
        
        
        return True