Merge Two Sorted binary trees
Last updated: December 15, 2025
Quick Overview
Given two sorted binary trees, merge them into a single binary tree that maintains the sorted order. The output tree should contain all the nodes from both input trees, and the resulting tree should be constructed such that an in-order traversal will yield a sorted sequence of values.
Capital One
December 15, 202524
7
399 solved
Given two sorted binary trees, merge them into a single binary tree that maintains the sorted order. The output tree should contain all the nodes from both input trees, and the resulting tree should be constructed such that an in-order traversal will yield a sorted sequence of values.
Capital One uses this problem in the Technical Screen to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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 test this solution thoroughly?
- What happens if the input contains duplicates?
- Can you solve this in a single pass?
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Practice DSA ProblemsSample Answer
Problem Analysis
To merge two sorted binary trees into one sorted binary tree, we can leverage the properties of binary search trees (BSTs) where for each node, the left subtree contains nodes with values less than th...
Approach
- We will perform an in-order traversal of both trees simultaneously.
- Start at the root of both trees. Compare the values of the current nodes from both trees.
- If one tree has a node with a s...
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