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 NUM such that no two adjacent elements will be the same or find out if it not possible.

For example:

Input: arr[] = {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 elements which are the same.

How to find the pre order traversal of a tree?
State complexity of merge sort
Questions based on radix sort

You are given an array of 'N' integers, and a positive integer 'K'. You need to determine if it is possible to divide the array into 'K' non-empty subsets such that the sum of elements of each subset is equal.

Note:

1. The array can have duplicate elements.

2. Each of the array elements must belong to exactly one of the 'K' subsets.

3. The elements chosen for a subset may not be contiguous in the array.

You are given an array 'arr' containing 'n' non-negative integers.

Your task is to partition this array into two subsets such that the absolute difference between subset sums is minimum.

You just need to find the minimum absolute difference considering any valid division of the array elements.

Note:

1. Each array element should belong to exactly one of the subsets.

2. Subsets need not always be contiguous.
For example, for the array : [1, 2, 3], some of the possible divisions are 
   a) {1,2} and {3}
   b) {1,3} and {2}.

3. Subset-sum is the sum of all the elements in that subset. 

Example:

Input: 'n' = 5, 'arr' = [3, 1, 5, 2, 8].

Ouput: 1

Explanation: We can partition the given array into {3, 1, 5} and {2, 8}. 
This will give us the minimum possible absolute difference i.e. (10 - 9 = 1).

You are given a positive integer ‘N’. Your task is to print all prime numbers less than or equal to N.

Note: A prime number is a natural number that is divisible only by 1 and itself. Example - 2, 3, 17, etc.

You can assume that the value of N will always be greater than 1. So, the answer will always exist.