Missing integer variation - O(n) solution needed [closed]

Answer 1

My 100/100 solution

  public int solution(int[] A) {
        Arrays.sort(A);
        for (int i = 1; i < 1_000_000; i++) {
            if (Arrays.binarySearch(A, i) < 0){
                return i;
            }
        }
        return -1;
    }