Greedy on array
Last updated: October 14, 2025
Quick Overview
Given an array of integers, implement a greedy algorithm to find the maximum sum of non-adjacent elements. You need to return the maximum sum that can be obtained by selecting elements from the array such that no two selected elements are adjacent. The input will be an array of integers, and the output should be a single integer representing the maximum sum.
Twitter/X
October 14, 202598
9
1,517 solved
Given an array of integers, implement a greedy algorithm to find the maximum sum of non-adjacent elements. You need to return the maximum sum that can be obtained by selecting elements from the array such that no two selected elements are adjacent. The input will be an array of integers, and the output should be a single integer representing the maximum sum.
Twitter/X uses this problem in the Take-home Project 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
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
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?
- Can you optimize the space complexity of your solution?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to find the maximum sum of non-adjacent elements from a given array of integers. This is a classic dynamic programming problem where we can utilize a greedy algorithmic approac...
Approach
- Initialization: Start by defining two variables:
incl(to store the maximum sum including the current element) andexcl(to store the maximum sum excluding the current element). Initialize ...
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