Lesson 4 Part 2 (MissingInteger) - MechyKola/Codility-lessons GitHub Wiki

Write a function:

class Solution { public int solution(int[] A); }

that, given a non-empty zero-indexed array A of N integers, returns the minimal positive integer (greater than 0) that does not occur in A.

For example, given: A[0] = 1 A[1] = 3 A[2] = 6 A[3] = 4 A[4] = 1 A[5] = 2

the function should return 5.

Assume that:

    N is an integer within the range [1..100,000];
    each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].

Complexity:

    expected worst-case time complexity is O(N);
    expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).

Elements of input arrays can be modified.