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First Missing Positive
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First Missing Positive

HardPython

Problem

First Missing Positive (LeetCode 41).

Asked in the coding stage. Given an unsorted list of integers, return the smallest positive integer that does not appear in the list.

Input and Output

Implement def first_missing_positive(nums):. The function receives a list of integers and returns an integer. Modify the list in place if useful.

Constraints

  • 1 <= len(nums) <= 10^4
  • -10^6 <= nums[i] <= 10^6
  • The input list may be modified in place
  • Use O(n) time and O(1) extra space

Function Signature

def first_missing_positive(nums):
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