Implement Priority Queue with streaming input

Last updated: March 14, 2026

Quick Overview

Design and implement a priority queue that efficiently handles streaming input, allowing for the insertion of elements and retrieval of the highest priority element in O(log n) time. The priority queue should support operations such as `insert(value, priority)` and `extract_max()`, with the ability to handle a continuous stream of data. Ensure that your implementation can manage dynamic input sizes and maintain the correct order of priorities.

Zscaler
Coding & Algorithms
Software Engineer
Zscaler
March 14, 2026
Software Engineer
Technical Screen
Coding & Algorithms
Hard

8

3

129 solved


Design and implement a priority queue that efficiently handles streaming input, allowing for the insertion of elements and retrieval of the highest priority element in O(log n) time. The priority queue should support operations such as `insert(value, priority)` and `extract_max()`, with the ability to handle a continuous stream of data. Ensure that your implementation can manage dynamic input sizes and maintain the correct order of priorities.

Coding interviews at Zscaler 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
Hash maps and frequency counting
Sorting and searching
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Tree structures and recursion
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • What if the input doesn't fit in memory?
  • What happens if the input contains duplicates?
  • Can you solve this iteratively instead of recursively (or vice versa)?
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Sample Answer
Problem Analysis

To implement a priority queue that efficiently handles streaming input, we can utilize a heap data structure, specifically a max-heap. This is because a max-heap allows us to maintain the highest ...

Approach
  1. Data Structure: Use a max-heap to store elements based on their priority. Each node in the heap will consist of a value and its corresponding priority.

  2. Insert Operation: When inserting ...


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