30DaysOfCode of HackerRank -Javascript 💻

My Java Scripts solutions for the 30 Days Of Code challenges on HackerRank.

Day 0 - Hello, World.

Input Format: A single line of text denoting (the variable whose contents must be printed).

Output Format: Print Hello, World. on the first line, and the contents of on the second line.

Sample Input

  Welcome to 30 Days of Code!

Sample Output

  Hello, World. 
  Welcome to 30 Days of Code!

Day 1 - Data Types

Task: The variables i, d, and s are already declared and initialized for you. You must:

1. Declare variables: one of type int, one of type double, and one of type String.
2. Read lines of input from stdin (according to the sequence given in the Input Format section below) and initialize your variables.
3. Use the operator to perform the following operations:
   • Print the sum of plus your int variable on a new line.
   • Print the sum of plus your double variable to a scale of one decimal place on a new line.
   • Concatenate with the string you read as input and print the result on a new line.

Input Format:

• The first line contains an integer that you must sum with .
• The second line contains a double that you must sum with .
• The third line contains a string that you must concatenate with .

Output Format: Print the sum of both integers on the first line, the sum of both doubles (scaled to decimal place) on the second line, and then the two concatenated strings on the third line.

Sample Input

  12
  4.0
  is the best place to learn and practice coding!

Sample Output

  16
  8.0
  HackerRank is the best place to learn and practice coding!

Day 2 - Operators

Task: Given the meal price (base cost of a meal), tip percent (the percentage of the meal price being added as tip), and tax percent (the percentage of the meal price being added as tax) for a meal, find and print the meal's total cost. Round the result to the nearest integer.

Input Format: There are lines of numeric input: 1. The first line has a double, meal_cost (the cost of the meal before tax and tip). 2. The second line has an integer, tip_percent (the percentage of meal_cost being added as tip). 3. The third line has an integer, tax_percent (the percentage of meal_cost being added as tax).

Output Format: print the meal's total cost.

Sample Input

  12.00
  20
  8

Sample Output

  15

Day 3 - Day 3: Intro to Conditional Statements

Task: Given an integer, , perform the following conditional actions:

• If n is odd, print Weird
• If n is even and in the inclusive range of 2 to 5, print Not Weird
• If n is even and in the inclusive range of 6 to 20, print Weird
• If n is even and greater than 20, print Not Weird

Input Format: A single line containing a positive integer, n.

Output Format: Print Weird if the number is weird; otherwise, print Not Weird.

Sample Input 0

  3

Sample Output 0

  Weird

Sample Input 1

  24

Sample Output 1

  Not Weird

Day 4 - Class vs. Instance

Task: Write a Person class with an instance variable, age, and a constructor that takes an integer, initialAge, as a parameter. The constructor must assign initialAge to age after confirming the argument passed as initialAge is not negative; if a negative argument is passed as initialAge, the constructor should set age to 0 and print Age is not valid, setting age to 0.. In addition, you must write the following instance methods:

1. yearPasses() should increase the age instance variable by 1.
2. amIOld() should perform the following conditional actions:
   • If age < 13, print You are young..
   • If age >= 13 and age < 18, print You are a teenager..
   • Otherwise, print You are old..

Input Format: Input is handled for you by the stub code in the editor. The first line contains an integer, T (the number of test cases), and the T subsequent lines each contain an integer denoting the age of a Person instance.

Output Format: Complete the method definitions provided in the editor so they meet the specifications outlined above; If your methods are implemented correctly, each test case will print 2 or 3 lines (depending on whether or not a valid initialAge was passed to the constructor).

Sample Input

  4
  -1
  10
  16
  18

Sample Output

  Age is not valid, setting age to 0.
  You are young.
  You are young.

  You are young.
  You are a teenager.

  You are a teenager.
  You are old.

  You are old.
  You are old.

Day 5 - Loops

Task: Given an integer, n, print its first 10 multiples. Each multiple n x i (where 1<= i >= 10) should be printed on a new line in the form: n x i = result.

Input Format: A single integer, n.

Output Format: Print 10 lines of output; each line i (where 1<= i >= 10) contains the result of n x i in the form:

• n x i = result.

Sample Input

  2

Sample Output

  2 x 1 = 2
  2 x 2 = 4
  2 x 3 = 6
  2 x 4 = 8
  2 x 5 = 10
  2 x 6 = 12
  2 x 7 = 14
  2 x 8 = 16
  2 x 9 = 18
  2 x 10 = 20
  

Day 6 - Let's Review

Task: Given a string, S, of length N that is indexed from 0 to N-1, print its even-indexed and odd-indexed characters as 2 space-separated strings on a single line (see the Sample below for more detail).

Input Format: The first line contains an integer, T (the number of test cases). Each line i of the T subsequent lines contain a string, S.

Output Format: For each String S_j (where 0 <= j<= T-1), print S_j 's even-indexed characters, followed by a space, followed by S_j's odd-indexed characters.

Sample Input

  2
  Hacker
  Rank

Sample Output

  Hce akr
  Rn ak
  

Day 7 - Arrays

Task: Given an array, A, of N integers, print A's elements in reverse order as a single line of space-separated numbers.

Input Format: The first line contains an integer, N(the size of our array). The second line contains N space-separated integers that describe array A's

Output Format: Print the elements of array A in reverse order as a single line of space-separated numbers.

Sample Input

  4
  1 4 3 2

Sample Output

  2 3 4 1
  

Day 8 - Arrays

Task: Given n names and phone numbers, assemble a phone book that maps friends' names to their respective phone numbers. You will then be given an unknown number of names to query your phone book for. For each name queried, print the associated entry from your phone book on a new line in the form name=phoneNumber; if an entry for name is not found, print Not found instead.

Input Format: The first line contains an integer, n, denoting the number of entries in the phone book. Each of the n subsequent lines describes an entry in the form of n space-separated values on a single line. The first value is a friend's name, and the second value is an 8-digit phone number.

After the n lines of phone book entries, there are an unknown number of lines of queries. Each line (query) contains a name to look up, and you must continue reading lines until there is no more input.

Output Format: On a new line for each query, print Not found if the name has no corresponding entry in the phone book; otherwise, print the full name and phonenumber in the format name=phoneNumber.

Sample Input

  3
  sam 99912222
  tom 11122222
  harry 12299933
  sam
  edward
  harry

Sample Output

  sam=99912222
  Not found
  harry=12299933
  

Day 9 - Recursion 3

Task: A recursive function is a nonleaf function that calls itself. The factorial function can be written as a recursive function call. Recall that factorial(n) = n × (n – 1) × (n – 2) × … × 2 × 1. The factorial function can be rewritten recursively as factorial(n) = n × factorial(n – 1). The factorial of 1 is simply 1.

Input Format: A single integer, n (the argument to pass to factorial).

Output Format: the factorial of n

Explanation:Consider the following steps. After the recursive calls from step 1 to 3, results are accumulated from step 3 to 1.

1. factorial(3) = 3 × factorial(2) = 3 * 2 = 6 (The answer)
2. factorial(2) = 2 × factorial(1) = 2 * 1 = 2
3. factorial(1) = 1

Sample Input

  3

Sample Output

  6
  

Day 10 - Binary Numbers

Task: Given a base-10 integer, n, convert it to binary (base- 2). Then find and print the base-10 integer denoting the maximum number of consecutive 1's in n's binary representation. When working with different bases, it is common to show the base as a subscript.

Input Format: A single integer, n.

Output Format: Print a single base-10 integer that denotes the maximum number of consecutive 1's in the binary representation of n.

Explanation:_The binary representation of 5₁₀ is 101₂, so the maximum number of consecutive 1's is 1. _

Sample Input

  5

Sample Output

  1
  

Day 11 - 2D Arrays

Context Given a 6 x 6 2D Array, A:

  1 1 1 0 0 0
  0 1 0 0 0 0
  1 1 1 0 0 0
  0 0 0 0 0 0
  0 0 0 0 0 0
  0 0 0 0 0 0

We define an hourglass in A to be a subset of values with indices falling in this pattern in A's graphical representation:

  a b c
    d
  e f g

There are 16 hourglasses in A, and an hourglass sum is the sum of an hourglass' values.

Task: Calculate the hourglass sum for every hourglass in A, then print the maximum hourglass sum.

Input Format: There are 6 lines of input, where each line contains 6 space-separated integers that describe the 2D Array A.

Output Format: Print the maximum hourglass sum in A.

Explanation: A contains the following hourglasses:

  1 1 1   1 1 0   1 0 0   0 0 0
    1       0       0       0
  1 1 1   1 1 0   1 0 0   0 0 0

  0 1 0   1 0 0   0 0 0   0 0 0
    1       1       0       0
  0 0 2   0 2 4   2 4 4   4 4 0

  1 1 1   1 1 0   1 0 0   0 0 0
    0       2       4       4
  0 0 0   0 0 2   0 2 0   2 0 0

  0 0 2   0 2 4   2 4 4   4 4 0
    0       0       2       0
  0 0 1   0 1 2   1 2 4   2 4 0

The hourglass with the maximum sum (19) is:

  2 4 4
    2
  1 2 4

Sample Input

  1 1 1 0 0 0
  0 1 0 0 0 0
  1 1 1 0 0 0
  0 0 2 4 4 0
  0 0 0 2 0 0
  0 0 1 2 4 0

Sample Output

  19
  

Day 12 - Inheritance

Task: You are given two classes, Person and Student, where Person is the base class and Student is the derived class. Observe that Student inherits all the properties of Person.

Complete the Student class by writing the following:

• A Student class constructor, which has parameters:

  1. A string, firstName.
  2. A string, lastName.
  3. An integer, idNumber.
  4. An integer array (or vector) of test scores, scores.

• A char calculate() method that calculates a Student object's average and returns the grade character representative of their calculated average:

  Letter	Average(a)
  O	90 <= a >= 100
  E	80 <= a > 90
  A	70 <= a > 80
  P	55 <= a > 70
  D	40 <= a > 55
  T	a < 40

Input Format: The first line contains firstName, lastName, and idNumber, separated by a space. The second line contains the number of test scores. The third line of space-separated integers describes scores.

Output Format: Print printPerson() function output and calculate() function.

Sample Input

  Heraldo Memelli 8135627
  2
  100 80

Sample Output

  Name: Memelli, Heraldo
  ID: 8135627
  Grade: O
  

Day 13 - Abstract Classes

Task: Given a Book class and a Solution class, write a MyBook class that does the following:

• Inherits from Book
• Has a parameterized constructor taking these 3 parameters:
  1. string title
  2. string author
  3. int price
• Implements the Book class' abstract display() method so it prints these 3 lines:
  1. Title, a space, and then the current instance's title.
  2. Author, a space, and then the current instance's author.
  3. Price, a space, and then the current instance's price.

Input Format: _ The Solution class creates a Book object and calls the MyBook class constructor (passing it the necessary arguments). It then calls the display method on the Book object._

Output Format: The void display() method should print and label the respective title, author, and price of the MyBook object's instance (with each value on its own line) like so:

Sample Input

  The Alchemist
  Paulo Coelho
  248

Sample Output

  Title: The Alchemist
  Author: Paulo Coelho
  Price: 248
  

Day 14 - Scope

Task: Complete the Difference class by writing the following:

• A class constructor that takes an array of integers as a parameter and saves it to the __elements instance variable.
• A computeDifference method that finds the maximum absolute difference between any 2 numbers in __elements and stores it in the maximumDifference instance variable.

Input Format: Reads in 2 lines of input. The first line contains N, the size of the elements array. The second line has N space-separated integers that describe the __elements array.

Output Format: The Solution class will print the value of the maximumDifference instance variable.

Sample Input

  STDIN   Function
  -----   --------
  3       __elements[] size N = 3
  1 2 5   __elements = [1, 2, 5]

Sample Output

  4
  

Day 15 - Linked List

Task: it creates a new Node (pass data as the Node constructor argument) and inserts it at the tail of the linked list referenced by the head parameter. Once the new node is added, return the reference to the head node.

Input Format: The first line contains T, the number of elements to insert. Each of the next T lines contains an integer to insert at the end of the list.

Output Format: Return a reference to the head node of the linked list.

Sample Input

  STDIN   Function
  -----   --------
  4       T = 4
  2       first data = 2
  3
  4
  1       fourth data = 1

Sample Output

  2 3 4 1
  

Day 16: Exceptions - String to Integer

Task: Read a string, S, and print its integer value; if S cannot be converted to an integer, print Bad String.

Input Format: A single string, S.

Output Format: Print the parsed integer value of S, or Bad String if S cannot be converted to an integer.

Sample Input 0

  3

Sample Output 0

  3

Sample Input 1

  za

Sample Output 1

  Bad String