leetcode/work/1/Easy/Hash Table/290.word-pattern.py

"""
290. Word Pattern
Difficulty: Easy
https://leetcode.com/problems/word-pattern/

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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. Specifically:

        • Each letter in pattern maps to exactly one unique word in s.

        • Each unique word in s maps to exactly one letter in pattern.

• No two letters map to the same word, and no two words map to the
same letter.



Example 1:

Input: pattern = "abba", s = "dog cat cat dog"

Output: true

Explanation:

The bijection can be established as:

        • 'a' maps to "dog".

        • 'b' maps to "cat".

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.
"""


class Solution:
    def wordPattern(self, pattern: str, s: str) -> bool:
        if len(pattern) != len(s.split()):
            return False

        words = s.split()
        map = {}

        for i in range(len(pattern)):
            c = pattern[i]
            w = words[i]

            if c in map and map[c] != w:
                return False
            else:
                map[c] = w

        return len(set(pattern)) == len(set(words))