What is wrong with my Java solution to Codility MissingInteger? [closed]

Answer 1

I have done the answer inspired by the answer of Denes but a simpler one.

int counter[] = new int[A.length];

// Count the items, only the positive numbers
for (int i = 0; i < A.length; i++)
    if (A[i] > 0 && A[i] <= A.length)
        counter[A[i] - 1]++;

// Return the first number that has count 0
for (int i = 0; i < counter.length; i++)
    if (counter[i] == 0)
        return i + 1;

// If no number has count 0, then that means all number in the sequence
// appears so the next number not appearing is in next number after the
// sequence.
return A.length + 1;