First Missing Integer Asked in: Model N InMobi Amazon

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 Given an unsorted integer array, find the first missing positive integer.

Example:

Given [1,2,0] return 3,

[3,4,-1,1] return 2,

[-8, -7, -6] returns 1

Your algorithm should run in O(n) time and use constant space.


Solution:

class Solution:

    # @param A : list of integers

    # @return an integer

    def firstMissingPositive(self, A):

        A=set(A)

        i=1

        while(1):

            if i not in A:

                return i

            i+=1

        return i+1

            

Solution ScreenShot:


           

      

        


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