Two Pointers on matrix
Last updated: September 20, 2025
Quick Overview
Given a matrix of integers, implement the Two Pointers technique to find two elements in the matrix that sum up to a specific target value. The function should return the coordinates of these two elements as a tuple (row1, col1, row2, col2) or indicate that no such pair exists. The matrix is guaranteed to have at least two elements, and the target will be an integer.
TikTok
September 20, 20256
3
141 solved
Given a matrix of integers, implement the Two Pointers technique to find two elements in the matrix that sum up to a specific target value. The function should return the coordinates of these two elements as a tuple (row1, col1, row2, col2) or indicate that no such pair exists. The matrix is guaranteed to have at least two elements, and the target will be an integer.
TikTok 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
- Can you solve this iteratively instead of recursively (or vice versa)?
- What if the input doesn't fit in memory?
- How would you parallelize this solution?
- Can you solve this in a single pass?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to find two distinct elements in a matrix that sum up to a specific target value. The two pointers technique is suitable here, particularly because we can treat the matrix as a...
Approach
- Traverse through each element in the matrix using two nested loops — the outer loop for the first pointer and the inner loop for the second pointer.
- For each element, calculate the complement a...
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