word_pattern.py

'''
Given a pattern and a string 's', find if 's' follows the same pattern.

Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in s.

Example 1:
Input: pattern = "abba", s = "dog cat cat dog"
Output: true

Example 2:
Input: pattern = "abba", s = "dog cat cat fish"
Output: false

Example 3:
Input: pattern = "aaaa", s = "dog cat cat dog"
Output: false

Constraints:

1 <= pattern.length <= 300
pattern contains only lower-case English letters.
1 <= s.length <= 3000
s contains only lowercase English letters and spaces ' '.
s does not contain any leading or trailing spaces.
All the words in s are separated by a single space.
'''

class Solution:
    def wordPattern(self, pattern, s):
        words = s.split()
        if len(words) != len(pattern):
            return False
        
        char_to_word = {}
        word_to_char = {}

        for char, word in zip(pattern, words):
            if char in char_to_word:
                if char_to_word[char] != word:
                    return False
            else:
                char_to_word[char] = word

            if word in word_to_char:
                if word_to_char[word] != char:
                    return False
            else:
                word_to_char[word] = char

        return True

sol = Solution()
pattern = "abba"
s = "dog cat cat fish"

print(sol.wordPattern(pattern, s))