class Solution(object):
    def wordPattern(self, pattern, s):
        """
        :type pattern: str
        :type s: str
        :rtype: bool
        """



        # This line splits the input string s into a list of words using space (" ") as the delimiter. For example, if s is "cat dog bird", words would be ["cat", "dog", "bird"].
        words = ssplit(" ")
        # This line checks if the length of the pattern (which is assumed to be a string) is not equal to the length of the words list. If they are not of the same length, it means there cannot be a one-to-one mapping between characters in the pattern and words, so the function returns False.
        if len(pattern) != len(words):
            return False
        # These lines initialize two dictionaries: charToWord to map characters from the pattern to words, and wordToChar to map words to characters from the pattern.
        charToWord= {}
        wordToChar ={}
        # This line iterates through the characters of pattern and the words in words simultaneously. It pairs each character with its corresponding word using the zip() function.
        for char, word in zip (pattern, words):
            # This line checks if the current character from the pattern already exists in the charToWord dictionary and if the corresponding word is not the same as the current word. If it's not the same, it means there's a mismatch, so the function returns False.
            if char in charToWord and charToWord[char] != word:
                return False
            # Similar to the previous line, this one checks if the current word already exists in the wordToChar dictionary and if the corresponding character is not the same as the current character. If it's not the same, it means there's a mismatch, so the function returns False.
            if word in wordToChar and wordToChar[word] != char:
                return False
            # These lines update the mappings in charToWord and wordToChar dictionaries, assigning the current character to the current word and vice versa.
            charToWord[char] = word
            wordToChar[word] = char
        #If the function hasn't returned False earlier, it means all characters in the pattern can be mapped to corresponding words in words, and vice versa, so it returns True, indicating a successful mapping.
        return True




# -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

pattern = "abba" s = "dog cat cat dog" After splitting the string s by spaces, we get the list of words: python Copy code words = ["dog", "cat", "cat", "dog"] 

Now, let's execute the line if char in charToWord and charToWord[char] != word: with the first iteration of the loop, where char = 'a' and word = 'dog'.

Initially, charToWord is empty and wordToChar is empty. python Copy code charToWord = {} wordToChar = {} 

In the first iteration of the loop: char = 'a' word = 'dog' The condition if char in charToWord evaluates to False because charToWord is empty. 

Thus, we don't enter the block of code associated with this condition.

In subsequent iterations, charToWord and wordToChar will get populated. But for the first iteration, there's no prior mapping, so we don't return False at this point. 

This line of code ensures that if a character in the pattern has already been mapped to a different word, it returns False, indicating a mismatch.

However, in this example, there's no such mismatch for the first character 'a', so the function continues executing.
