Problem
Implementation and application of Binary Search Tree (BST).
1. Develop a pseudo code to use BST to sort an array in the decreasing order, at the same time remove those duplicated elements and negative elements. For example, given an input array [18, 13, -7, -9, 4, 2, 18, 6, 4, 10, 4, -7], the output should be [18, 13, 10, 6, 4, 2] (8 points).
2. Discuss the time complexity and storage complexity of your code.