SDE - 1

You have been given an array/list 'PREORDER' representing the preorder traversal of a BST with 'N' nodes. All the elements in the given array have distinct values.

Your task is to construct a binary search tree that matches the given preorder traversal.

A binary search tree (BST) is a binary tree data structure that has the following properties:

• The left subtree of a node contains only nodes with data less than the node’s data.
• The right subtree of a node contains only nodes with data greater than the node’s data.
• Both the left and right subtrees must also be binary search trees.

Note:

It is guaranteed that a BST can be always constructed from the given preorder traversal. Hence, the answer will always exist.

Example:

From PREORDER = [20, 10, 5, 15, 13, 35, 30, 42] , the following BST can be constructed:

Given a string of integers ‘bin’. Return 'true' if the string represents a valid binary number, else return 'false'. A binary number is a number that has only 0 or 1 in it.

You are given an array/list 'NUM' of integers. You are supposed to rearrange the elements of the given 'NUM' so that after rearranging the given array/list there are no two adjacent elements present in the rearranged 'NUM' which will be the same.

For example:

Input: NUM[] = {1,1,1,2,2,2} 
Output: {1,2,1,2,1,2}
Note: {2,1,2,1,2,1} is also valid because there are no two adjacent which are the same.

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