Code-Practice
Function 1
Time to test your basic knowledge in functions! Return the odds from a list:
odds([1,2,3,4,5]) #=> [1,3,5]
Function 2
Write a function that always returns 5
Sounds easy right? Just bear in mind that you can't use any of the following characters: 0123456789*+-/
Function 3
The company you work for has just been awarded a contract to build a payment gateway. In order to help move things along, you have volunteered to create a function that will take a float and return the amount formatting in dollars and cents.
39.99 becomes $39.99
The rest of your team will make sure that the argument is sanitized before being passed to your function although you will need to account for adding trailing zeros if they are missing (though you won't have to worry about a dangling period).
Function 4
Return product of numbers between a and b (both non-negative). If it's impossible then return 'Error' in JavaScript
Function 5 Can you find the needle in the haystack?
Write a function findNeedle() that takes an array full of junk but containing one "needle"
After your function finds the needle it should return a message (as a string) that says:
"found the needle at position " plus the index it found the needle, so:
findNeedle(['hay', 'junk', 'hay', 'hay', 'moreJunk', 'needle', 'randomJunk']) should return "found the needle at position 5"
Kata 6
Everybody knows the classic "half your age plus seven" dating rule that a lot of people follow (including myself). It's the 'recommended' age range in which to date someone.
minimum age <= your age <= maximum age #Task
Given an integer (1 <= n <= 100) representing a person's age, return their minimum and maximum age range.
This equation doesn't work when the age <= 14, so use this equation instead:
min = age - 0.10 * age max = age + 0.10 * age You should floor all your answers so that an integer is given instead of a float (which doesn't represent age). Return your answer in the form [min]-[max]
##Examples:
age = 27 => 20-40 age = 5 => 4-5 age = 17 => 15-20
kata 7
Deoxyribonucleic acid, DNA is the primary information storage molecule in biological systems. It is composed of four nucleic acid bases Guanine ('G'), Cytosine ('C'), Adenine ('A'), and Thymine ('T').
Ribonucleic acid, RNA, is the primary messenger molecule in cells. RNA differs slightly from DNA its chemical structure and contains no Thymine. In RNA Thymine is replaced by another nucleic acid Uracil ('U').
Create a function which translates a given DNA string into RNA.
For example:
"GCAT" => "GCAU" The input string can be of arbitrary length - in particular, it may be empty. All input is guaranteed to be valid, i.e. each input string will only ever consist of 'G', 'C', 'A' and/or 'T'.
kata 8n Given a list of the following major Houses of Westeros and their respective mottos:
var houses = [ {name: "Targaryen", motto: "Fire and Blood"}, {name: "Stark", motto: "Winter is Coming"}, {name: "Bolton", motto: "Our Blades Are Sharp"}, {name: "Greyjoy", motto: "We Do Not Sow"}, {name: "Tully", motto: "Family, Duty, Honor"}, {name: "Arryn", motto: "As High as Honor"}, {name: "Lannister", motto: "Hear Me Roar!"}, {name: "Tyrell", motto: "Growing Strong"}, {name: "Baratheon", motto: "Ours is the Fury"}, {name: "Martell", motto: "Unbowed, Unbent, Unbroken"} ];```
Write a function that, when passed the name of a House, returns its motto. For instance: motto("Tyrell")
should return "Growing Strong"
If passed an invalid House name, the script should return an empty string.
// kata 9
he aspect ratio of an image describes the proportional relationship between its width and its height. Most video shown on the internet uses a 16:9 aspect ratio, which means that for every pixel in the Y, there are roughly 1.77 pixels in the X (where 1.77 ~= 16/9). As an example, 1080p video with an aspect ratio of 16:9 would have an X resolution of 1920, however 1080p video with an aspect ratio of 4:3 would have an X resolution of 1440.
Write a function that accepts arbitrary X and Y resolutions and converts them into resolutions with a 16:9 aspect ratio that maintain equal height. Round your answers up to the nearest integer.
This kata is part of a series with Aspect Ratio Cropping - Part 2 .
Example
374 × 280 pixel image with a 4:3 aspect ratio.
Aspect ratio 4 3 example
500 × 280 pixel image with a 16:9 aspect ratio.
// kata 10
Write function bmi that calculates body mass index (bmi = weight / height ^ 2).
if bmi <= 18.5 return "Underweight"
if bmi <= 25.0 return "Normal"
if bmi <= 30.0 return "Overweight"
if bmi > 30 return "Obese"
// kata 11
The Collatz conjecture (also known as 3n+1 conjecture) is a conjecture that applying the following algorithm to any number we will always eventually reach one:
[This is writen in pseudocode]
if(number is even) number = number / 2
if(number is odd) number = 3*number + 1
#Task
Your task is to make a function hotpo that takes a positive n as input and returns the number of times you need to perform this algorithm to get n = 1.
#Examples
hotpo(1) returns 0
(1 is already 1)
hotpo(5) returns 5
5 -> 16 -> 8 -> 4 -> 2 -> 1
hotpo(6) returns 8
6 -> 3 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1
hotpo(23) returns 15
23 -> 70 -> 35 -> 106 -> 53 -> 160 -> 80 -> 40 -> 20 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1
// Kata 12
An AI has infected a text with a character!!
This text is now fully mutated to this character.
If the text or the character are empty, return an empty string.
There will never be a case when both are empty as nothing is going on!!
Note: The character is a string of length 1 or an empty string.
// kata 13
Create a simple calculator that given a string of operators (), +, -, *, / and numbers separated by spaces returns the value of that expression
Example:
Calculator().evaluate("2 / 2 + 3 * 4 - 6") # => 7
Remember about the order of operations! Multiplications and divisions have a higher priority and should be performed left-to-right. Additions and subtractions have a lower priority and should also be performed left-to-right.
// kata 14
Write a function that returns true if the number is a "Very Even" number.
If a number is a single digit, then it is simply "Very Even" if it itself is even.
If it has 2 or more digits, it is "Very Even" if the sum of it's digits is "Very Even".
#Examples:
input(88) => returns false -> 8 + 8 = 16 -> 1 + 6 = 7 => 7 is odd
input(222) => returns true
input(5) => returns false
input(841) => returns true -> 8 + 4 + 1 = 13 -> 1 + 3 => 4 is even
Note: The numbers will always be 0 or positive integers!
// kata 15
Write a function that checks whether a credit card number is correct or not, using the Luhn algorithm.
The algorithm is as follows:
From the rightmost digit, which is the check digit, moving left, double the value of every second digit; if the product of this doubling operation is greater than 9 (e.g., 8 × 2 = 16), then sum the digits of the products (e.g., 16: 1 + 6 = 7, 18: 1 + 8 = 9) or alternatively subtract 9 from the product (e.g., 16: 16 - 9 = 7, 18: 18 - 9 = 9).
Take the sum of all the digits.
If the total modulo 10 is equal to 0 (if the total ends in zero) then the number is valid according to the Luhn formula; else it is not valid.
The input is a string with the full credit card number, in groups of 4 digits separated by spaces, i.e. "1234 5678 9012 3456"
Don´t worry about wrong inputs, they will always be a string with 4 groups of 4 digits each separated by space.
Examples
valid_card?("5457 6238 9823 4311") # True
valid_card?("5457 6238 9323 4311") # False