HackerRank Python Solution - Debugging - Default Arguments

• Python supports a useful concept of default argument values. For each keyword argument of a function, we can assign a default value which is going to be used as the value of said argument if the function is called without it. For example, consider the following increment function:

def increment_by(n, increment=1):
    return n + increment

• The functions work like this:

>>> increment_by(5, 2)
7
>>> increment_by(4)
5
>>>

• Debug the given function print_from_stream using the default value of one of its arguments.

HackerRank Python Solution - Debugging - Words Score

• In this challenge, the task is to debug the existing code to successfully execute all provided test files.
• Consider that vowels in the alphabet are a, e, i, o, u, and y.
• Function score_words takes a list of lowercase words as an argument and returns a score as follows:
• The score of a single word is 2 if the word contains an even number of vowels. Otherwise, the score of this word is 1. The score for the whole list of words is the sum of scores of all words in the list.
• Debug the given function score_words such that it returns a correct score.
• Your function will be tested on several cases by the locked template code.

HackerRank Python Solution - Closures and Decorators - Name Directory

• Let's use decorators to build a name directory! You are given some information about N people. Each person has a first name, last name, age, and sex. Print their names in a specific format sorted by their age in ascending order i.e. the youngest person's name should be printed first. For two people of the same age, print them in the order of their input.

• For Henry Davids, the output should be:

Mr. Henry Davids

• For Mary George, the output should be:

Ms. Mary George

HackerRank Python Solution - Closures and Decorators - Standardize Mobile Number Using Decorators

• Let's dive into decorators! You are given N mobile numbers. Sort them in ascending order then print them in the standard format shown below:

+91 xxxxx xxxxx

• The mobile numbers may have +91, 91, or 0 written before the actual 10-digit number. Alternatively, there may not be any prefix at all.

Input Format:

• The first input line contains an integer N, the number of mobile phone numbers. N lines follow each having a mobile number.

HackerRank Python Solution - Functionals - Reduce Function

Given a list of rational numbers, find their product.

Concept:

• The reduce() function applies a function of two arguments cumulatively on a list of objects in succession from left to right to reduce it to one value. Say you have a list, say [1,2,3] and you have to find its sum.

>>> reduce(lambda x, y : x + y,[1,2,3])
6

HackerRank Python Solution - Functionals - Validating Email Addresses with a Filter

• You are given an integer N followed by N email addresses. Your task is to print a list containing only valid email addresses in lexicographical order.
• Valid email addresses must follow these rules:
• It must have the username@websitename.extension format type.
• The username can only contain letters, digits, dashes and underscores [a-z],[A-Z],[0-9],[_-].
• The website name can only have letters and digits [a-z],[A-Z],[0-9].
• The extension can only contain letters [a-z],[A-Z].
• The maximum length of the extension is 3.

HackerRank Python Solution - Functionals - Map and Lambda Function

Let's learn some new Python concepts! You have to generate a list of the first Fibonacci numbers, 0 being the first number. Then, apply the map function and a lambda expression to cube each Fibonacci number and print the list.

Concept:

• The map() function applies a function to every member of an iterable and returns the result. It takes two parameters: first, the function that is to be applied, and second, the iterables.
• Let's say you are given a list of names, and you have to print a list that contains the length of each name.

>> print (list(map(len, ['Tina', 'Raj', 'Tom'])))  
[4, 3, 3]  

HackerRank Python Solution - Strings - Merge the Tools!

Consider the following:

• A string, s, of length n where s=c₀c₁...c_n-1.
• An integer, k, where k is a factor of n.

We can split s into n/k substrings where each substring, t_i, consists of a contiguous block of k characters in s. Then, use each t_i to create string u_i such that:

• The characters in u_i are a subsequence of the characters in t_i.
• Any repeat occurrence of a character is removed from the string such that each character in u_i occurs exactly once. In other words, if the character at some index j in t_i occurs at a previous index < j in t_i, then do not include the character in string u_i.

Given s and k, print n/k lines where each line i denotes string u_i.

HackerRank Python Solution - Strings - The Minion Game

• Kevin and Stuart want to play 'The Minion Game'.

Game Rules:

• Both players are given the same string, S.
• Both players have to make substrings using the letters of the string S.
• Stuart has to make words starting with consonants.
• Kevin has to make words starting with vowels.
• The game ends when both players have made all possible substrings.

Scoring:

• A player gets a +1 point for each occurrence of the substring in the string S.

HackerRank Python Solution - Strings - Alphabet Rangoli

• You are given an integer, N. Your task is to print an alphabet rangoli of size N. (Rangoli is a form of Indian folk art based on the creation of patterns.)
• Different sizes of alphabet rangoli are shown below:

#size 3

----c----
--c-b-c--
c-b-a-b-c
--c-b-c--
----c----