Leetcode - Word Pattern Solution

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

Example 4:

Input: pattern = "abba", s = "dog dog dog dog"
Output: false


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

Solution in python

class Solution:
    def wordPattern(self, pattern: str, s: str) -> bool:
        def recreate(s):
            index = 0
            word_map = {}
            for i in s:
                x = word_map.get(i,-1)
                if x!=-1:
                    yield x
                    yield index
                    word_map[i] = index
        s = s.split()
        if len(s) != len(pattern):
            return False
        return all(x==y for x,y in zip(recreate(pattern),recreate(s)))

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