Find shortest distance in binary tree
Last updated: December 12, 2025
Quick Overview
Given a binary tree, write a function to find the shortest distance between two nodes in the tree. The function should take two node values as input and return the shortest distance as an integer. If either of the nodes does not exist in the tree, return -1.
Vercel
December 12, 2025579
14
2,077 solved
Given a binary tree, write a function to find the shortest distance between two nodes in the tree. The function should take two node values as input and return the shortest distance as an integer. If either of the nodes does not exist in the tree, return -1.
Coding interviews at Vercel focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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
- Can you optimize the space complexity of your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
- Can you solve this in a single pass?
- What is the worst-case input for your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To find the shortest distance between two nodes in a binary tree, we can leverage the properties of binary trees, particularly their hierarchical structure. The key is to first determine the lowest co...
Approach
- Find the Lowest Common Ancestor (LCA): We will create a helper function that recursively traverses the tree to find the LCA of the two node values. If we find either node, we return it. If both...
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