SDE - 1

You're given a string 'S' consisting of "{", "}", "(", ")", "[" and "]" .

Return true if the given string 'S' is balanced, else return false.

For example:

'S' = "{}()".

There is always an opening brace before a closing brace i.e. '{' before '}', '(' before ').
So the 'S' is Balanced.

You are given a starting position for a rat which is stuck in a maze at an initial point (0, 0) (the maze can be thought of as a 2-dimensional plane). The maze would be given in the form of a square matrix of order 'N' * 'N' where the cells with value 0 represent the maze’s blocked locations while value 1 is the open/available path that the rat can take to reach its destination. The rat's destination is at ('N' - 1, 'N' - 1). Your task is to find all the possible paths that the rat can take to reach from source to destination in the maze. The possible directions that it can take to move in the maze are 'U'(up) i.e. (x, y - 1) , 'D'(down) i.e. (x, y + 1) , 'L' (left) i.e. (x - 1, y), 'R' (right) i.e. (x + 1, y).

Note:

Here, sorted paths mean that the expected output should be in alphabetical order.

For Example:

Given a square matrix of size 4*4 (i.e. here 'N' = 4):
1 0 0 0
1 1 0 0
1 1 0 0
0 1 1 1 
Expected Output:
DDRDRR DRDDRR 
i.e. Path-1: DDRDRR and Path-2: DRDDRR

The rat can reach the destination at (3, 3) from (0, 0) by two paths, i.e. DRDDRR and DDRDRR when printed in sorted order, we get DDRDRR DRDDRR.

Ninja has to implement a data structure ”TRIE” from scratch. Ninja has to complete some functions.

1) Trie(): Ninja has to initialize the object of this “TRIE” data structure.

2) insert(“WORD”): Ninja has to insert the string “WORD”  into this “TRIE” data structure.

3) countWordsEqualTo(“WORD”): Ninja has to return how many times this “WORD” is present in this “TRIE”.

4) countWordsStartingWith(“PREFIX”): Ninjas have to return how many words are there in this “TRIE” that have the string “PREFIX” as a prefix.

5) erase(“WORD”): Ninja has to delete one occurrence of the string “WORD” from the “TRIE”.

Note:

1. If erase(“WORD”) function is called then it is guaranteed that the “WORD” is present in the “TRIE”.

2. If you are going to use variables with dynamic memory allocation then you need to release the memory associated with them at the end of your solution.

Can you help Ninja implement the "TRIE" data structure?

You have been given a root node of the binary search tree and a positive integer value. You need to perform an insertion operation i.e. inserting a new node with the given value in the given binary search tree such that the resultant tree is also a binary search tree.

If there can be more than one possible tree, then you can return any.

Note :

A binary search tree is a binary tree data structure, with the following properties :

    a. The left subtree of any node contains nodes with a value less than the node’s value.

    b. The right subtree of any node contains nodes with a value equal to or greater than the node’s value.

    c. Right, and left subtrees are also binary search trees.
It is guaranteed that,

    d. All nodes in the given tree are distinct positive integers.

    e. The given BST does not contain any node with a given integer value.

Example, below the tree, is a binary search tree.

Below the tree is not a BST as node ‘2’ is less than node ‘3’ but ‘2’ is the right child of ‘3’, and node ‘6’ is greater than node ‘5’ but it is in the left subtree of node ‘5’.

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