Grading policy:

3 Marks for writing correct code for finding a vertical piercing line which runs in O(n) time. Deduct 1 mark if algorithm takes more time.

7 marks for correct algorithm for computing boundary. Deduct 1 mark if algorithm takes more than O(n log n) time.

3 marks each for correct output of test cases (6 marks in total)

2 marks for indentation (total 2 marks)
2 marks for comments (total 2 marks)

Total marks: 20