SDE - 1

Design and implement a data structure for Least Recently Used (LRU) cache to support the following operations:

1. get(key) - Return the value of the key if the key exists in the cache, otherwise return -1.

2. put(key, value), Insert the value in the cache if the key is not already present or update the value of the given key if the key is already present. When the cache reaches its capacity, it should invalidate the least recently used item before inserting the new item.

You will be given ‘Q’ queries. Each query will belong to one of these two types:

Type 0: for get(key) operation.
Type 1: for put(key, value) operation.

Note :

1. The cache is initialized with a capacity (the maximum number of unique keys it can hold at a time).

2. Access to an item or key is defined as a get or a put operation on the key. The least recently used key is the one with the oldest access time.

You have been given a sorted array of length ‘N’. You need to construct a balanced binary search tree from the array. If there can be more than one possible tree, then you can return any.

Note:

1. A balanced binary tree is a binary tree structure in which the left and right subtrees of every node differ in height by no more than 1.

2. A binary search tree is a binary tree data structure, with the following properties
    a. The left subtree of any node contains nodes with value less than the node’s value.
    b. The right subtree of any node contains nodes with values equal to or greater than the node’s value.
    c. Right, and left subtrees are also binary search trees.

Example:

Below tree, is a balanced binary search tree

Below tree is not a balanced tree as the height of the left subtree and right subtree of node ‘5’ differs by more than 1. Moreover, the tree is also not a BST as node ‘2’ is less than node ‘3’ but ‘2’ is the right child of ‘3’.

You have been given an array/list 'HEIGHTS' of length ‘N. 'HEIGHTS' represents the histogram and each element of 'HEIGHTS' represents the height of the histogram bar. Consider that the width of each histogram is 1.

You are supposed to return the area of the largest rectangle possible in the given histogram.

For example :

In the below histogram where array/list elements are {2, 1, 5, 6, 2, 3}.

The area of largest rectangle possible in the given histogram is 10.

You are present at point ‘A’ which is the top-left cell of an M X N matrix, your destination is point ‘B’, which is the bottom-right cell of the same matrix. Your task is to find the total number of unique paths from point ‘A’ to point ‘B’.In other words, you will be given the dimensions of the matrix as integers ‘M’ and ‘N’, your task is to find the total number of unique paths from the cell MATRIX[0][0] to MATRIX['M' - 1]['N' - 1].

To traverse in the matrix, you can either move Right or Down at each step. For example in a given point MATRIX[i] [j], you can move to either MATRIX[i + 1][j] or MATRIX[i][j + 1].

You are given a string S of words. Your task is to count the occurrence of each word present in the string S. A word is a sequence of one or more non-space characters, and there can be multiple spaces between two words, and also there can be leading or trailing spaces in a string S.

For Example:

For the given string  “what we think we become”

“what”,” think”, and “become” occurs 1 time, and “we” occurs 2 times in the given string.

You are given two strings 'str1' and 'str1'.

You have to tell whether these strings form an anagram pair or not.

The strings form an anagram pair if the letters of one string can be rearranged to form another string.

Pre-requisites:

Anagrams are defined as words or names that can be formed by rearranging the letters of another word. Such as "spar" can be formed by rearranging letters of "rasp". Hence, "spar" and "rasp" are anagrams. 

Other examples include:

'triangle' and 'integral'
'listen' and 'silent'

Note:

Since it is a binary problem, there is no partial marking. Marks will only be awarded if you get all the test cases correct.