LeetCode Top Interview 150

290. Word Pattern

Easy

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

Constraints:

• 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

from typing import Dict

class Solution:
    def wordPattern(self, pattern: str, s: str) -> bool:
        map: Dict[str, str] = {}
        words = s.split()
        if len(words) != len(pattern):
            return False
        for i in range(len(pattern)):
            if pattern[i] not in map:
                if words[i] in map.values():
                    return False
                map[pattern[i]] = words[i]
            else:
                if words[i] != map[pattern[i]]:
                    return False
        return True

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