Word pattern

Leetcode/python/String/290. Word Pattern.py

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+class Solution:
+    def wordPattern(self, pattern: str, s: str) -> bool:
+        char_to_word: dict[str, str] = {}
+
+        words = s.split()
+        word_used = set()
+        if len(words) != len(pattern):
+            return False
+        for index, word in enumerate(words):
+            char_pattern = pattern[index]
+            if char_pattern in char_to_word:
+                if char_to_word[char_pattern] != word:
+                    return False
+
+            else:
+                if word in word_used:
+                    return False
+                char_to_word[char_pattern] = word
+                word_used.add(word)
+        return True
+
+
+if __name__ == "__main__":
+    s = Solution()
+    assert s.wordPattern(pattern="abba", s="dog cat cat dog") == True
+    assert s.wordPattern(pattern="aaaa", s="dog cat cat dog") == False
+    assert s.wordPattern(pattern="abba", s="dog cat cat fish") == False
+    assert s.wordPattern("abba", "dog dog dog dog") == False