This problem set finds the smallest positive integer that does not exist in an array

SmallestPostiveInteger.py

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Write a function:

    def solution(A)

that, given an array A of N integers, returns the smallest positive integer (greater than 0) that does not occur in A.

For example, given A = [1, 3, 6, 4, 1, 2], the function should return 5.

Given A = [1, 2, 3], the function should return 4.

Given A = [−1, −3], the function should return 1.

Write an efficient algorithm for the following assumptions:

        N is an integer within the range [1..100,000];
        each element of array A is an integer within the range [−1,000,000..1,000,000].
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def solution(A):
    # write your code in Python 3.6
    A.sort()
    max = A[ len(A) -1 ]
    
    if max < 1 :
        return 1
    for i in range(1, max + 1) :
       if i not in A :
           return i
    return max + 1