Word Ladder Shortest Transformation Sequence
Last updated: March 3, 2025
Quick Overview
Find the shortest transformation sequence from start word to end word, changing one letter at a time, with each intermediate word in the dictionary.
ByteDance
March 3, 202512
3
4,818 solved
Find the shortest transformation sequence from start word to end word, changing one letter at a time, with each intermediate word in the dictionary.
Graph BFS is a top pattern at ByteDance. Word Ladder tests BFS with implicit graph construction from a dictionary.
What the Interviewer Expects
- Model as a BFS problem on an implicit graph
- Implement efficient neighbor generation
- Use bidirectional BFS for optimization
- Handle the dictionary efficiently with wildcard patterns
- Return the shortest path length
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you return the actual transformation path?
- How would you find all shortest paths?
- What if the dictionary is very large (millions of words)?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
This problem can be modeled as a Breadth-First Search (BFS) on an implicit graph where each word is a node, and an edge exists between two nodes (words) if they differ by exactly one letter. The BFS a...
Approach
- Build a word dictionary: Store all words in a set for O(1) average time complexity on lookups.
- Generate neighbors: For a given word, generate all possible words by changing each letter t...
Submit Your Answer
