290-word-pattern

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Description

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.

Solution(Python)

class Solution:
    def wordPattern(self, pattern: str, s: str) -> bool:
        s = s.split(" ")
        wordhashmap = {}
        charhashmap = {}
        if len(s) != len(pattern):
            return False
        for ch, word in zip(pattern, s):
            if word not in wordhashmap:
                wordhashmap[word] = ch
            elif wordhashmap[word] != ch:
                return False

            if ch not in charhashmap:
                charhashmap[ch] = word
            elif charhashmap[ch] != word:
                return False
        return True