Write a method that takes a binary tree and an array of items as input, and it returns a binary search tree (BST) as output. The binary tree contains n nodes and doesn't need to be balanced. The array contains n unique items which are mutually comparable. The method should build a binary search tree of n nodes. The binary search tree should contain the items. The structure of the binary search tree should be same as the structure of the binary tree. Explain your function in detail and give theoretical run time complexity analysis of that method in the report.