Word Pattern
Given a pattern and a string s, determine if s follows the same pattern.
A string follows a pattern if there is a one-to-one correspondence between each character in the pattern and each word in the string.
Each character maps to exactly one word, and each word maps to exactly one character.
Example 1
Input
abba dog cat cat dog
Output
true
Explanation
'a' maps to "dog" and 'b' maps to "cat". The mapping is consistent and one-to-one.
Example 2
Input
abba dog cat cat fish
Output
false
Explanation
The last word is "fish" instead of "dog", so the pattern is violated.
Constraints
Hints:
Hint 1
Split the string into words and first check if the number of words matches the length of the pattern.
Hint 2
Use two hash maps: one for character-to-word mapping and another for word-to-character mapping to maintain a one-to-one correspondence.
Author & Technical Reviewer
Technically reviewed by: ExamAdda Technical Review Team
Technical Reviewers, ExamAdda
Software engineers at ExamAdda who check every article's definitions, complexity claims and code examples before and after publishing.
Published
Aug 6, 2026
Last updated
Aug 7, 2026
Content Verification Methodology
Definitions and complexity claims were checked against authoritative computer-science references. Code examples were compiled and tested with standard, boundary and edge-case inputs.
Expected Output