Interview Cookbook

This repository will house several code snippets and useful resources for Data Structures, Algorithms and Object-Oriented Concepts.

Feel free to contribute to this repository and make a pull request!

C

• Nth root of a number
• Determine whether a number is a Fibonacci number
• Distance between a point and a plane in 3-D
• Print factors of N in pairs
• Probability of rain on (n+1)th day
• Slope of a given number
• Sum of all prime divisors of a number
• sum of series whose 'i'th term is (i^k - (i-1)^k)

Java

• Power of 2 - A two player game
• Find number of palindromes of n-digits
• Find maximum among x^(y^2) or y^(x^2) where x and y are given

Recursion

• Flood fill algorithm - C++
• Count all possible paths from top left to bottom right of a mXn matrix
• Josephus problem
• Special Keyboard problem
• Water Overflow

Matrices

• Spiral traversal of a m x n Matrix
• Find difference between sums of two diagonals of a matrix
• Interchange first and last rows of a given matrix
• Check whether a given matrix is symmetric or not
• Rotate a given matrix in clockwise direction by one element each
• Sort a given matrix
• Given 1's, 2's, 3's ....k's print them in zig zag way.

Arrays

• Split an array into two having equal sums
• Find the highest value using 4 operators +, *, (, )
• Print alternate prime numbers till N
• Minimum number of Changes required to transform an array into an arithmetic progression
• Seperate 0s and 1s from an array using a single array only
• Maximum length of segments of 0's and 1's

Linked Lists

• General Implementation
• Delete element based on position
• Delete element based on key
• Reverse Linkedlist
• Find middle element
• Merge two unsorted lists
• Remove Duplicate elements
• Union and intersection of two linked lists
• Detect loop in a linked list
• Swap two nodes without swapping data

Circular Linked Lists

• Sorted insertion for circular linked list
• Implementation of a double ended queue
• Convert Binary Tree to circular Doubly linked list
• Split Circular linked list into two halves

Doubly Linked Lists

• General Implementation
• Delete a given node in DLL
• Merge sort
• Reverse a given DLL
• Create a DLL from a given ternary tree
• Sort and insert a node into a sorted DLL - cpp
• Swap kth node from the beginning with the kth node from the end

Sorting Algorithms

• BubbleSort
• InsertionSort
• SelectionSort
• QuickSort
• MergeSort

Searching Algorithms

• BinarySearch
• RotatedBinarySearch
• TernarySearch

String Programs

• Highest Palindrome formed by changing k-digits
• Multiply positional values of two strings and check if the modulus(47) is same for both values
• Find the smallest window in a string containing all characters of another string
• Reverse String
• Palindrone String
• Regular Expression
• Remove Duplicates
• Remove White Spaces
• String Segmentation
• Next Highest Permutation Of A String
• Anagram
• Count the occurences of anagrams, given a word and a pattern

Python

• Power of 2 - A two player game

Stacks

• Getting started with Stacks
• Implementation of infix to postfix
• Implement stack using arrays
• Conversion of an infix expression to postfix
• Reverse a string using stacks
• Evaluate postfix expression

Queues

• Getting started with Queues
• Implementing queues with Linkedlists
• FIFO page replacement algorithm
• Rearrange the elements by interleaving the first half of the queue with the second half of the queue.

JavaScript(ECMAScript 2015)

Data Structures :

Arrays

• Kadane's Algorithm
• Missing numbers in a sequence
• Sub-array sum equals k
• Largest Sub-array with contiguous 0's and 1's
• Largest number formed by an array
• Sort elements of an array by its frequency of occurence
• Given a non-empty array of digits representing a non-negative integer, increment one to the integer.
• Find all subsets of a given array
• Check if a given sudoku board is valid
• Rotate an array k times to the right
• Buy and sell stock
• Rotate a 2-D image clockwise

Linked Lists

• Middle element of a Linked List
• Reverse a Linked List
• Rotate a Linked List
• Check if Linked List is Palindrome
• Implement queue using LinkedList
• Implement stack using LinkedList
• Detect Loop in linked list
• Merge K sorted linked lists

Graphs

• General Implementation
• BFS traversal
• DFS traversal

Algorithms :

Sorting Algorithms

• BubbleSort
• InsertionSort
• SelectionSort
• QuickSort
• MergeSort

Searching Algorithms

• BinarySearch
• BinarySearchTree

Greedy Algorithms

• GreedyKnapsack

String Algorithms

• Palindrome

Miscellaneous problems

• Hamming Distance between two numbers
• Reward students having a great attendance record

Maps & Filters in ES6

Maps :

• A map is an object that lets us store key-value pairs where both the keys and the values can be objects, primitive values, or a combination of both of these.

• Description - The map() method creates a new array with the results of calling a provided function on every element in the calling array.

 const numbers = [3,6,9,12];
 const newNumbers = numbers.map(num => num/3);

Here,we are just going over the values in ‘numbers’ array, halving them and creating a brand new array with the new values [1,2,3,4].

• Creating a map - The below code snippet creates an empty map student with no key-value pairs.

 const students = new Map();
 console.log(students);

 Map{}

We can add key-values to a map by using the .set() method.

 const students = new Map();
 students.set('[email protected]',{
    'firstName': 'Adithya',
    'lastName':'NR',
    'course':'Udacity React Nanodegree'
 });
 students.set('[email protected]',{
    'firstName': 'Bapusaheb',
    'lastName':'Patil',
    'course':'Udacity Android Nanodegree'
 });
 console.log(students);

 Map{'[email protected]' => Object{...},'[email protected]' => Object{...}}

The .set() method takes two arguments - the key,which is used to reference the second argument,the value.

• Removing a key-value pair using the .delete() method.

 students.delete('[email protected]');
 console.log(students);

 Map{'[email protected]' => Object{firstName:'Bapusaheb',lastName:'Patil',course:'Udacity Android Nanodegree'}}

• We can use the .clear() method to remove all key-value pairs from the Map.

 students.clear();
 console.log(students);

 Map{}

Filter :

The filter() method creates a new array with all elements that pass the test implemented by the provided function.

 const names = ['Adithya','Aditya','Arjun','Abhishek','Bapusaheb'];
 const peopleWithShortNames = names.filter(name => name.length < 8);

 //Output - peopleWithShortNames = ['Adithya','Aditya','Arjun']

Just like map, ‘filter’ is nothing special. It’s going over values in ‘words’ array checking which values pass the test, in this case which name has length lesser than 8 characters and then returns a new array with those names.

Interview Questions

HTML5

Q : What is the purpose of the DocType in HTML5?
A : The DocType element specifies the HTML version to the browser. It usually appears in the first line of code of an HTML page. Unlike the earlier versions/standards of HTML, DocType has got a simplified format in HTML5.

Q : What are the various media tags introduced in HTML5?
A :

• <audio> – It specifies sound content.
• <video> – It links to a video.
• <source> – This tag specified the source of video and audio links.
• <embed> – It acts as a container for external applications.
• <track> – This element defines tracks for video and audio.

Q : What is SVG?
A : SVG which stands for Scalable Vector Graphics as recommended by the W3C is used to display vector graphics across the web.All elements and attributes of SVG support animation and use XML format.They provide high quality and responsive graphics.

Q : What is a canvas?
A : Canvas is an HTML5 element which can draw graphics on the fly with the help of JavaScript. The <canvas> element can only contain graphics. It supports a number of methods for drawing paths, boxes, circles, text, and images.

Q : How do set an image as a draggable element?
A : To set an image as draggable, initialize the draggable attribute with true.

    <img draggable="true" src="...">

Q : What is web storage in HTML?
A : HTML5 brought this new ability to store web pages within the browser cache. This web storage is not only faster than the cookies but secured too. It is capable of storing a large amount of data without compromising the performance of the website.

Q : What Is The Difference Between LocalStorage And SessionStorage Objects?
A :

• The <localStorage> object doesn’t have an expiry for the stored data whereas the <sessionStorage> object keeps it only for a single session.
• The <localStorage> object doesn’t have a provision to delete the data upon closing of browser window whereas the <sessionStorage> object clears it simultaneously with the window closing down.

CSS3

Q : How does CSS3 support the Responsive Web Designing?
A : Media Queries ;-)

Q : What are the different types of CSS?
A :

• Embedded – It adds the CSS styles using the <style> attribute inside the HTML file.
• Inline – It adds the CSS to the HTML elements. (ie: <h1 style="text-align=center;font-size:36px;">Hola!</h1>)
• Linked/External – It adds an external CSS file to the HTML document via the <link> tag.

Q : How does an ID selector differ from a class selector?
A : An ID Selector finds and modifies the style to only a single UNIQUE element whereas a class selector may apply to any number of HTML elements.An ID Selector is given higher priority over a class selector.

Q : How do you implement a rounded border?
A : By using the border-radius property.

Q : What is webkit in CSS3?
A : Webkit is a core software component which is responsible for rendering HTML and CSS in browsers like Safari and Chrome. There are other similar rendering engines like Gecko for Mozilla, Presto for Opera, and Edge for IE.
To enable Webkit on a web page, it requires prefixing the <-webkit> keyword with CSS values.

.className {
    -webkit-box-shadow: 0px 0px 5px 0px #ffffff;
    box-shadow: 0px 0px 5px 0px #ffffff;
}

Q : What are transitions in CSS?
A : CSS3 transitions help to create easy and fast animation effects. They not only give us control to change the value of a property but also let it proceed slowly for the given duration.

transition, transition-delay, transition-duration, transition-property, and transition-timing-function.

Q : What are Media Queries?
A : Media queries are one of the latest features of CSS3 used to define responsive styles for devices of different screen sizes.
They are the powerful CSS tool which makes it easy to create responsive design for tablets, desktop, mobiles devices. They can help adjusting the Height, Width, Viewport, Orientation and Resolution.

@media screen and (min-width: 480px) {
    body {
        background-color: #ffffff;
    }
}

Q : What are Pseudo-classes in CSS?
A : A Pseudo-Class is a CSS technique to set the style when the element changes its state.
i.e : Editing the style upon mouse hover event,Set the style when an element is on focus or Apply different styles for visited/unvisited links.

selector:pseudo-class {
    property:value;
}

Q : Explain the working of z-index?
A : The z-index is a CSS property which defines the stack order of web elements. Higher order elements will appear before any lower order element.

Note – The z-index only applies to the positioned elements. For example, position:absolute, position:relative, or position:fixed.
    div {
        position: absolute;
        left: 10px;
        top: 10px;
        z-index: -1;
    }

Bash

• Write steps to execute a script as soon as system starts
• Write a script to Auto Increment variable in bash
• Write a line to edit line with specific pattern in shell script
• Write a code to display path of executable file in Linux
• How to disable sound on Linux systems?

How to contribute

Read the Contributing Guidelines and make your contribution. Follow the instructions!

Contributors