Word Pattern

From LeetCode

problem description / no solution provided

Solution in Python3

class Solution:
    def wordPattern(self, pattern: str, st: str) -> bool: 
        words = st.split()
        return (
            len(words) == len(pattern) 
            and len(set(pattern)) 
                == len(set(words)) 
                == len(set(zip(words, pattern)))
        )

I am lucky to get

Runtime: 36 ms, faster than 76.09% of Python3 online submissions for Word Pattern.

Time Complexity

\(O(n)\), where \(n\) is the number of words.

Variant

Dictionary

class Solution:
    def wordPattern(self, pattern: str, st: str) -> bool:
        word_to_pattern = {}
        words = st.split()
        if len(words) != len(pattern):
            return False
        for i, p in enumerate(pattern):
            if words[i] in word_to_pattern:
                if word_to_pattern[words[i]] != p:
                    return False
            else:
                if p in word_to_pattern.values():
                    return False
                word_to_pattern[words[i]] = p
            
        return True

Runtime: 36 ms, faster than 76.09% of Python3 online submissions for Word Pattern.