Implement Priority Queue with O(1) space
Last updated: March 25, 2026
Quick Overview
Implement a priority queue that supports the operations of inserting an element, deleting the highest priority element, and peeking at the highest priority element, all while using O(1) space. Your implementation should handle integer priorities and allow for dynamic insertion and removal of elements. The output should be the highest priority element when peeking, and the queue should maintain the correct order of priorities after each operation.
Datadog
March 25, 20260
13
233 solved
Implement a priority queue that supports the operations of inserting an element, deleting the highest priority element, and peeking at the highest priority element, all while using O(1) space. Your implementation should handle integer priorities and allow for dynamic insertion and removal of elements. The output should be the highest priority element when peeking, and the queue should maintain the correct order of priorities after each operation.
Coding interviews at Datadog 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
- 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 modify your solution to handle streaming input?
- Can you optimize the space complexity of your solution?
- What if the input doesn't fit in memory?
- What happens if the input contains duplicates?
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Problem Analysis
To implement a priority queue that operates in O(1) space, we need to consider that traditional data structures like heaps or balanced trees generally require O(n) space for storage. Given the constra...
Approach
- Data Structure: Use a single variable to keep track of the highest priority seen so far. Use another variable to hold the highest priority element.
- Insertion: When inserting an element, ...
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