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First Missing Positive

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Description

https://leetcode.com/problems/first-missing-positive/description/

Solution

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class Solution:
    def firstMissingPositive(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if nums is None or len(nums) == 0:
            return 1
        
        for i in range(len(nums)):
            while nums[i] != i + 1 and nums[i] <= len(nums) and nums[i] > 0 and nums[nums[i] - 1] != nums[i]:
                temp = nums[i]
                nums[i] = nums[temp - 1]
                nums[temp - 1] = temp
                print (nums)
        
        for i in range(len(nums)):
            if nums[i] != i + 1:
                return i + 1
            
        return len(nums) + 1