SDE - 1

You are given a 2D board('N' rows and 'M' columns) of characters and a string 'word'.

Your task is to return true if the given word exists in the grid, else return false. The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring.

Note:

The same letter cell should not be used more than once.

For Example:

For a given word “design” and the given 2D board 
[[q’, ‘v’, ‘m’, ‘h’],
 [‘d’, ‘e’, ‘s’, ‘i’],
 [‘d’, ‘g’, ‘f’, ‘g’],
 [‘e’, ‘c’, ‘p’, ‘n’]]

The word design can be formed by sequentially adjacent cells as shown by the highlighted color in the 2nd row and last column.

Given a leaderboard of a game with the following ranking pattern:

The player with the highest score is ranked number 1 on the leaderboard.

Players who have equal scores receive the same ranking number, and the next player(s) receive the immediately following ranking number.

You are given game scores of a player of ‘M’ rounds. Your task is to return the position obtained in each round.

Note:

The leaderboard scores are in descending order.
The game scores are given in ascending order.

Design a HashSet without using any built-in hash table libraries.

Implement the following public functions :

1) Constructor: It initializes the data members as required.

2) add(value): It inserts an element into the HashSet. The function takes one argument which is the value that needs to be added and returns nothing

3) contains(value): It checks whether the element exists in the HashSet or not. The function takes one argument which is the value that needs to be searched for in the HashSet. The function returns true if the element exists, otherwise returns false.

4) remove(value): It removes an element from the HashSet. The function takes one argument which is the value that needs to be removed from the HashSet and returns the element which is being removed. If the element does not exist in the HashSet or if HashSet is empty, return -1.

Operations Performed on the HashSet:

Query-1 (Denoted by an integer 1)- Inserts an element in the HashSet

Query-2 (Denoted by an integer 2)- Returns a boolean value denoting whether the element is present in the HashSet or not.

Query-3 (Denoted by an integer 3)- Removes the element from the HashSet.

You are given an arbitrary binary tree, a node of the tree, and an integer 'K'. You need to find all such nodes which have a distance K from the given node and return the list of these nodes.

Distance between two nodes in a binary tree is defined as the number of connections/edges in the path between the two nodes.

Note:

1. A binary tree is a tree in which each node has at most two children. 
2. The given tree will be non-empty.
3. The given tree can have multiple nodes with the same value.
4. If there are no nodes in the tree which are at distance = K from the given node, return an empty list.
5. You can return the list of values of valid nodes in any order. For example if the valid nodes have values 1,2,3, then you can return {1,2,3} or {3,1,2} etc.

Example :

Consider this tree above. The target node is 5 and K = 3. The nodes at distance 1 from node 5 are {2}, nodes at distance 2 from node 5 are {1, 4} and nodes at distance 3 from node 5 are {6, 3}.