10960: Codility - Missing Integer
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Description
Find the smallest positive integer that does not occur in a given sequence.
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.
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.
Input
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 $[−1,000,000..1,000,000]$.
$N$ is an integer within the range $[1..100,000]$;
each element of array $A$ is an integer within the range $[−1,000,000..1,000,000]$.
Output
returns the smallest positive integer (greater than 0) that does not occur in A.
Sample 1 Input
6
1 3 6 4 1 2
Sample 1 Output
5
Sample 2 Input
3
1 2 3
Sample 2 Output
4
Sample 3 Input
2
-1 -3
Sample 3 Output
1