SDE - 1

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 are given a string 'str' of length 'N'.

Your task is to return the longest palindromic substring. If there are multiple strings, return any.

A substring is a contiguous segment of a string.

For example :

str = "ababc"

The longest palindromic substring of "ababc" is "aba", since "aba" is a palindrome and it is the longest substring of length 3 which is a palindrome. 

There is another palindromic substring of length 3 is "bab". Since starting index of "aba" is less than "bab", so "aba" is the answer.

You have been given a binary tree of integers.

Your task is to check if it is a binary heap tree or not.

Note:

A binary tree is a tree in which each parent node has at most two children. 

A binary heap tree has the following properties. 
1. It must be a complete binary tree. In the complete binary tree every level, except the last level, is completely filled and the last level is as far left as possible.

2. Every parent must be greater than its all children nodes.

For example:

Consider this binary tree:

Figure 1 is a complete binary tree because every level, except the last level, is completely filled and the last nodes are as far left as possible, and the level has 2 nodes both on the left side.

Figure 2 is not a complete binary tree because level 2 (level is 0 based) is not completely filled means the right child of the node (36) is missing.
There is another reason, in the last level, there can be one another node in between node (1) and node (14) to make the binary tree as far left as possible.

Note:

1. In the world of programming two types of binary heap tree possible:
   a. Min-heap - if all parents nodes are lesser than its children nodes.
   b. Max-heap - if all parents nodes greater than its children nodes, explained in the above figure-1.

2. In this problem binary heap tree is a binary max-heap tree.

The ninja visits an amusement park but finds himself confused because he wants to ride the rides such that he gets maximum fun. The amusement park has only one entrance that is root.

Each ride has a fun number assigned to it and ninja wants to maximize this fun but there is a rule in the park that no one is allowed to ride two directly connected rides.

As the ninja is smart and good in programming because he did a course from coding ninja, he found immediately that park rides are connected like binary tree where the root is the root of the binary tree. Help the ninja to get the maximum fun this time.

You have been given a Binary Tree of integers.

Your task is to print the Right view of it.

The right view of a Binary Tree is a set of nodes visible when the tree is viewed from the Right side and the nodes are printed from top to bottom order.

Implement Trie Data Structure to support these operations:

insert(word) - To insert a string "word" in Trie
search(word) - To check if string "word" is present in Trie or not.
startsWith(word) - To check if there is any string in the Trie that starts with the given prefix string "word".

Three type of queries denote these operations:

Type 1: To insert a string "word" in Trie.
1 word

Type 2: To check if the string "word" is present in Trie or not.
2 word

Type 3: To check if there is any string in the Trie that starts with the given prefix string "word".
3 word

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