Fullstack Developer

Given a source point (sx, sy) and a destination point (dx, dy), the task is to check if it is possible to reach the destination point using the following valid moves:

(a, b) -> (a + b, b)
(a, b) -> (a, a + b)

Your task is to find if it is possible to reach the destination point using only the desired moves or not.

For example:

For the coordinates, source point = (1, 1) and destination point = (3, 5)
The output will be true as the destination point can be reached using the following sequence of moves:
(1, 1) -> (1, 2) -> (3, 2) -> (3, 5)

You have been given a Binary Search Tree of integers with ‘N’ nodes. You are also given data of a node of this tree. Your task is to delete the given node from the BST.

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.

Example:

For the given BST, if we want to delete the node with data 5 :

The modified BST will be:

Please notice that another valid answer is:

Note :

1. The node which we want to delete will always be present in the given tree.

2. If after deletion the tree becomes empty, print -1.

You have been given a binary matrix of size 'N' * 'M' where each element is either 0 or 1. You are also given a source and a destination cell, both of them lie within the matrix.

Your task is to find the length of the shortest path from the source cell to the destination cell only consisting of 1s. If there is no path from source to destination cell, return -1.

Note:

1. Coordinates of the cells are given in 0-based indexing.
2. You can move in 4 directions (Up, Down, Left, Right) from a cell.
3. The length of the path is the number of 1s lying in the path.
4. The source cell is always filled with 1.

For example -

1 0 1
1 1 1
1 1 1
For the given binary matrix and source cell(0,0) and destination cell(0,2). Few valid paths consisting of only 1s are

X 0 X     X 0 X 
X X X     X 1 X 
1 1 1     X X X 
The length of the shortest path is 5.

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to return the list of all pairs of elements such that each sum of elements of each pair equals 'S'.

Note:

Each pair should be sorted i.e the first value should be less than or equals to the second value. 

Return the list of pairs sorted in non-decreasing order of their first value. In case if two pairs have the same first value, the pair with a smaller second value should come first.

You have been given a binary tree of integers with N number of nodes. Your task is to check if that input tree is a BST (Binary Search Tree) or not.

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.

Example :

Answer :

Level 1: 

All the nodes in the left subtree of 4 (2, 1, 3) are smaller 
than 4, all the nodes in the right subtree of the 4 (5) are 
larger than 4.

Level 2 :

For node 2:
All the nodes in the left subtree of 2 (1) are smaller than 
2, all the nodes in the right subtree of the 2 (3) are larger than 2.
For node 5:
The left and right subtrees for node 5 are empty.

Level 3:

For node 1:
The left and right subtrees for node 1 are empty.
For node 3:
The left and right subtrees for node 3 are empty.

Because all the nodes follow the property of a binary search tree, the above tree is a binary search tree.

Cache Memory.
Critical Section Problem.
Mutex vs Semaphore.

You are given a string 'S' and you need to return the length of the longest duplicate substring in the given string. The occurrence of duplicate sub-strings can overlap also.

If there are many longest duplicate sub-string return any of them.

You are given an array 'ARR' consisting of 'N' elements, and you need to find the maximum value of sum(i * ARR[i]) among all possible rotations of the given array. The rotations allowed are left rotation, and right rotation, and these rotations can be performed any number of times on the array.

Sum(i * ARR[i]) denotes the summation of all values (i * ARR[i]) for every 'i', where 0 <= 'i' <= 'N' - 1.

Note :

1. The array follows 0-based indexing.
2. In one rotation operation, all elements of the array will shift either towards the left or right by one index.
3. The element at the extreme left index (i.e. 0th index) will shift to the 'N-1'th index after applying one left rotation on the array and the rest all the elements will shift to the 'i-1'th index.
4. The element at the extreme right index (i.e. 'N-1'th index) will shift to the 0th index after applying one right rotation on the array and the rest of the elements will shift to the 'i' + 1'th index.