SDE - 1

You are given an array 'a' of size 'n'.

Print the Next Greater Element(NGE) for every element.

The Next Greater Element for an element 'x' is the first element on the right side of 'x' in the array, which is greater than 'x'.

If no greater elements exist to the right of 'x', consider the next greater element as -1.

For example:

Input: 'a' = [7, 12, 1, 20]

Output: NGE = [12, 20, 20, -1]

Explanation: For the given array,

- The next greater element for 7 is 12.

- The next greater element for 12 is 20. 

- The next greater element for 1 is 20. 

- There is no greater element for 20 on the right side. So we consider NGE as -1.

You have been given a binary tree of integers. You are supposed to find the left view of the binary tree. The left view of a binary tree is the set of all nodes that are visible when the binary tree is viewed from the left side.

Example:

The left view of the above binary tree is  {5, 7, 14, 25}.

You have been given a singly Linked List of 'N' nodes with integer data and an integer 'K'.

Your task is to remove the 'K'th node from the end of the given Linked List and return the head of the modified linked list.

Example:

Input : 1 -> 2 -> 3 -> 4 -> 'NULL'  and  'K' = 2
Output: 1 -> 2 -> 4 -> 'NULL'
Explanation:
After removing the second node from the end, the linked list become 1 -> 2 -> 4 -> 'NULL'.

You are given a Singly Linked List of integers. Return true if it has a cycle, else return false.

A cycle occurs when a node's next points back to a previous node in the list.

Example:

In the given linked list, there is a cycle, hence we return true.

You have been given a binary tree consisting of ‘N’ nodes where nodes have distinct integer values. Your task is to convert the given Binary Tree to a Binary Search Tree(BST).

Note: The conversion must be done in such a way that keeps the original structure of the Binary Tree.

A binary search tree (BST) is a binary tree data structure which 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. 

For Example:

For the given binary tree :

The BST will be:

Note: Each node is associated with a unique integer value.

You are given three rods (numbered 1 to 3), and ‘N’ disks initially placed on the first rod, one on top of each other in increasing order of size ( the largest disk is at the bottom). You are supposed to move the ‘N’ disks to another rod(either rod 2 or rod 3) using the following rules and in less than 2 ^ (N) moves.

1. You can only move one disk in one move. 
2. You can not place a larger disk on top of a smaller disk.
3. You can only move the disk at the top of any rod.    

Note :

You may assume that initially, the size of the ‘i’th disk from the top of the stack is equal to ‘i’, i.e. the disk at the bottom has size ‘N’, the disk above that has size ‘N - 1’, and so on. The disk at the top has size 1.

Example :

You have been given an array ‘levelOrder’ consisting of ‘N’ elements. The array represents the level order traversal of a Binary Search Tree(BST). You need to construct the BST from this level order 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.

For Example:

For the given level order traversal: 5 3 6 2 4 7 

The BST will be:

The Inorder Traversal of this BST is 2 3 4 5 6 7.