Coding.
First Missing Positive Test
The "First Missing Positive" challenge is a classic algorithmic problem used to assess a candidate's ability to design efficient solutions under strict time and space constraints. It tests their understanding of array manipulation, in-place algorithm
Summarize this test and see how it helps assess top talent with:
- Test type
- Coding
- Duration
- 29 min
- Level
- Advanced
- Questions
- 1
Skills measured
Array
Hash Table
Use of the First Missing Positive Test
You are given an unsorted integer array nums. Your task is to find the smallest positive integer that does not appear in the array.
- Your solution must run in O(n) time.
- It must use O(1) auxiliary space (excluding the input).
This problem requires thoughtful use of indexing and in-place data rearrangement to track existing positive integers efficiently.
Who is this test for?
This problem is particularly relevant for assessing candidates for software development roles that involve:
Algorithm design
Space/time optimization
Systematic debugging and edge case handling
It appears frequently in technical interviews because of its deceptively simple description and the optimal O(n) solution's complexity. Solving it demonstrates deep knowledge of array manipulation, in-place transformations, and the ability to write clean, performant code under constraints.
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The First Missing Positive Subject Matter Expert
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Sample reports
First Missing Positive Test
View sample questionsTop five hard skills interview questions for First Missing Positive
Here are the top five hard-skill interview questions tailored specifically for First Missing Positive. These questions are designed to assess candidates’ expertise and suitability for the role, along with skill assessments.
Frequently asked questions (FAQs) for First Missing Positive Test
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