Software Engineer

You are given an array ‘arr’ of ‘N’ distinct integers. Your task is to print all the non-empty subsets of the array.

Note: elements inside each subset should be sorted in increasing order. But you can print the subsets in any order, you don’t have to specifically sort them.

You are given an integer ‘N’, your task is to return the number of structurally unique BST's (binary search trees) which have exactly 'N' nodes of unique values from 1 to 'N'.

For example:

Given  ‘N’ = 2, The total number of BST’s is 2.

Note:

1. A binary search tree is a rooted binary tree whose internal nodes each store a key greater than all the keys in the node's left subtree and less than those in its right subtree.

2. A structurally unique binary search tree is a tree that has at least 1 node at a different position or with a different value compared to another binary search tree.

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