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Problem: Find the First K Missing Positive Numbers

easy
15 min
Explore how to identify the first k missing positive numbers from an unsorted integer array by applying cyclic sort. Understand constraints and implement an optimal solution running in O(n + k) time with O(k) space, preparing you for coding interviews.

Statement

Given an unsorted integer array, arr, of size n and an integer k, find the first k missing positive integers from the array, ignoring all negative numbers and zeros.

If the array does not contain enough missing positive numbers, add the next consecutive positive integers, starting from the smallest number greater than the largest value in the array, until exactly k missing positive numbers have been found.

Return the list of the first k missing positive integers, sorted in ascending order.

Constraints:

  • n=n = arr.length

  • 1k1041 \leq k \leq 10^4

  • 104-10^4 \leq arr[i] 104\leq 10^4

  • 0n1040 \leq n \leq 10^4

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Tap here to switch tabs
Problem
Submissions

Problem: Find the First K Missing Positive Numbers

easy
15 min
Explore how to identify the first k missing positive numbers from an unsorted integer array by applying cyclic sort. Understand constraints and implement an optimal solution running in O(n + k) time with O(k) space, preparing you for coding interviews.

Statement

Given an unsorted integer array, arr, of size n and an integer k, find the first k missing positive integers from the array, ignoring all negative numbers and zeros.

If the array does not contain enough missing positive numbers, add the next consecutive positive integers, starting from the smallest number greater than the largest value in the array, until exactly k missing positive numbers have been found.

Return the list of the first k missing positive integers, sorted in ascending order.

Constraints:

  • n=n = arr.length

  • 1k1041 \leq k \leq 10^4

  • 104-10^4 \leq arr[i] 104\leq 10^4

  • 0n1040 \leq n \leq 10^4

Unlock AI-Powered LearningUpgrade to smarter learning with instant explanations of Ask Agent, Personalized Interview Prep, Real-World Projects, 3 AI Mock Interviews per month, and Personalized Paths