SDE - 1

You are given an array of integers 'ARR' of length 'N' and an integer Target. Your task is to return all pairs of elements such that they add up to Target.

Note:

We cannot use the element at a given index twice.

Follow Up:

Try to do this problem in O(N) time complexity. 

You are given a linked list containing 'n' nodes, where every node in the linked list contains two pointers:

(1) ‘next’ which points to the next node in the list

(2) ‘random’ which points to a random node in the list or 'null'.

Your task is to create a 'deep copy' of the given linked list and return its head.

Note:

A 'deep copy' of a linked list means we do not copy the references of the nodes of the original linked list, rather for each node in the original linked list, a new node is created.

You are given an arbitrary array ‘arr’ consisting of N non-negative integers, where every element appears thrice except one. You need to find the element that appears only once.

You have been given an array/list ‘ARR’ consisting of ‘N’ positive integers. Your task is to return 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 'ARR', which is greater than ‘X’. If no such element exists to the right of ‘X’, then return -1.

For example:

For the given array 'ARR' = [7, 12, 1, 20]

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, the output is [12, 20, 20, -1].

You have been given a Binary Search Tree of integers. You are supposed to convert it to a greater sum tree such that the value of every node in the given BST is replaced with the sum of the values of all the nodes which are greater than the value of the current node in the tree.

A Binary Search Tree is a tree, whose internal nodes each store a value greater than all the values in the node's left subtree and less than those in its right subtree.

Note :

You need to modify the given tree only. You are not allowed to create a new tree.

For example:

For the given binary search tree

11 will be replaced by {15 + 29 + 35 + 40}, i.e. 119.
2 will be replaced by {7 + 11 + 15 + 29 + 35 + 40}, i.e. 137.
29 will be replaced by {35 + 40}, i.e. 75.
1 will be replaced by {2 + 7 + 11 + 15 + 29 + 35 + 40}, i.e. 139.
7 will be replaced by {11 + 15 + 29 + 35 + 40}, i.e. 130.
15 will be replaced by {15 + 29 + 35 + 40}, i.e. 104.
40 will be replaced by 0 {as there is no node with a value greater than 40}.
35 will be replaced by {40}, i.e. 40.

You are given a linked list of 'N' nodes where nodes can contain values 0, 1, and 2 only. Your task is to sort the linked list.

You are given a 2-dimensional array/list having N rows and M columns, which is filled with ones(1) and zeroes(0). 1 signifies land, and 0 signifies water.

A cell is said to be connected to another cell, if one cell lies immediately next to the other cell, in any of the eight directions (two vertical, two horizontal, and four diagonals).

A group of connected cells having value 1 is called an island. Your task is to find the number of such islands present in the matrix.

You have been given an N*M matrix filled with integer numbers, find the maximum sum that can be obtained from a path starting from any cell in the first row to any cell in the last row.

From a cell in a row, you can move to another cell directly below that row, or diagonally below left or right. So from a particular cell (row, col), we can move in three directions i.e.

Down: (row+1,col)
Down left diagonal: (row+1,col-1)
Down right diagonal: (row+1, col+1)