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https://github.com/tyn-tian/codewars-challenge-2024
A challenge that i will undertake in 2024 to strengthen my programming language and also hone my programming logic.
https://github.com/tyn-tian/codewars-challenge-2024
algorithms arrays fundamentals javascript mathematics php
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A challenge that i will undertake in 2024 to strengthen my programming language and also hone my programming logic.
- Host: GitHub
- URL: https://github.com/tyn-tian/codewars-challenge-2024
- Owner: Tyn-Tian
- Created: 2024-02-05T13:51:15.000Z (10 months ago)
- Default Branch: main
- Last Pushed: 2024-04-09T06:39:54.000Z (7 months ago)
- Last Synced: 2024-04-09T07:52:09.963Z (7 months ago)
- Topics: algorithms, arrays, fundamentals, javascript, mathematics, php
- Language: JavaScript
- Homepage:
- Size: 121 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
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README
# Codewars Challenge 2024 n/365
## Description
A challenge that i will undertake in 2024 to strengthen my JavaScript language and also hone my programming logic.
## Question and others
### 1. Even or Odd
Create a function that takes an integer as an argument and return **"Even"** for even numbers or **"Odd"** for odd numbers.
- Difficulty: _8 kyu_
- Tags:
- Mathematics
- Fundamentals
- Link: [Even or Odd](https://www.codewars.com/kata/53da3dbb4a5168369a0000fe)
### 2. Multiply
This code does not execute properly. Try to figure out why.
- Difficulty: _8 kyu_
- Tags:
- Debugging
- Fundamentals
- Link: [Multiply](https://www.codewars.com/kata/50654ddff44f800200000004)
### 3. Return Negative
In this simple assignment you are given a number and have to make it negative. But maybe the number is already negative?
**Examples**
```javascript
makeNegative(1); // return -1
makeNegative(-5); // return -5
makeNegative(0); // return 0
makeNegative(0.12); // return -0.12
```
**Notes**
- The number can be negative already, in which case no change is required.
- Zero (0) is not checked for any specific sign. Negative zeros make no mathematical sense.
---
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Link: [Return Negative](https://www.codewars.com/kata/55685cd7ad70877c23000102)
### 4. Sum of positive
You get an array of numbers, return the sum of all of the positives ones.
Example **[1,-4,7,12]** => **1 + 7 + 12 = 20**
Note: if there is nothing to sum, the sum is default to 0.
- Difficulty: _8 kyu_
- Tags:
- Arrays
- Fundamentals
- Link: [Sum of positive](https://www.codewars.com/kata/5715eaedb436cf5606000381)
### 5. Reversed Strings
Completed the solution so that it reverses the string passed into it.
```javascript
'world' => 'dlrow'
'word' => 'drow'
```
- Difficulty: _8 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Reversed Strings](https://www.codewars.com/kata/5168bb5dfe9a00b126000018)
### 6. Convert boolean values to strings 'Yes' or 'No'
Complete the method that takes a boolean value and return a **"Yes"** string for **true**, or a **"No"** string for **false**.
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Link: [Convert boolean values to string 'Yes' or 'No'](https://www.codewars.com/kata/53369039d7ab3ac506000467)
### 7. Convert a Number to a String!
We need a function that can transform a number (integer) into a string.
What ways of achieving this do you know?
**Examples (input --> output)**
```javascript
123 --> "123"
999 --> "999"
-100 --> "-100"
```
- Difficulty: _8 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Convert a String to a Number!](https://www.codewars.com/kata/5265326f5fda8eb1160004c8)
### 8. Vowel Count
Return the number (count) of vowels in the given string.
We will consider **a**,**e**,**i**,**o**,**u** as vowels for this Kata (but not **y**).
The input will only consist of lower case letters and/or spaces.
- Difficulty: _7 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Vowel Count](https://www.codewars.com/kata/54ff3102c1bad923760001f3)
### 9. Disemvowel Trolls
Troll are attacking your comment section!
A common way to deal with this situation is to remove all of the vowels from the trolls' comments, neutralizing the threat.
Your task is to write a function that takes a string and return a new string with all vowels removed.
For example the string "This website is for losers LOL!" would become "ths wbst s fr lsrs LL!".
Note: for this kata **y** isn't considered a vowel.
- Difficulty: _7 kyu_
- Tags:
- Strings
- Regular Expressions
- Fundamentals
- Link: [Disemvowel Trolls](https://www.codewars.com/kata/52fba66badcd10859f00097e)
### 10. Square Every Digit
Welcome. In this kata, you are asked to square every digit of a number and concatenate them.
For example, if we run 9119 through the function, 811181 will come out, because 9^2 is 81 and 1^2 is 1. (81-1-1-81)
Example #2: An input of 765 will/should return 493625 because 7^2 is 49, 6^2 is 36, and 5^2 is 25. (49-36-25)
**Note**: The function accepts an integer and return an integer.
Happy Coding!
- Difficulty: _7 kyu_
- Tags:
- Mathematics
- Fundamentals
- Link: [Square Every Digit](https://www.codewars.com/kata/546e2562b03326a88e000020)
### 11. Highest and Lowest
In this little assignment you are given a string of spacec separated numbers, and have to return the highest and lowest number.
**Examples**
```javascript
higAndLow("1 2 3 4 5"); // return "5 1"
higAndLow("1 2 -3 4 5"); // return "5 -3"
higAndLow("1 9 3 4 -5"); // return "9 -5"
```
**Notes**
- All numebers are valid **Int32**, no need to validate them.
- There will always be at least one number in the input string.
- Output string must be two numbers separated by a single space, and highest number is first.
---
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Strings
- Link: [Highest and Lowest](https://www.codewars.com/kata/554b4ac871d6813a03000035)
### 12. Descending Order
You task is to make a function that can take non-negative integer as an argument and return it with its digits in descending order. Essentially, rearrange the digits to create the highest possible number.
**Examples:**
Input: **42145** Output: **54421**
Input: **145263** Output: **654321**
Input: **123456789** Output: **987654321**
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Descending Order](https://www.codewars.com/kata/5467e4d82edf8bbf40000155)
### 13. Get the Middle Character
You are going to be given a word. Your job is to return the middle character of the word. If the word's length is odd, return the middle character. If the word's length is even, return the middle 2 characters.
**Examples:**
```javascript
Kata.getMiddle("test") should return "es"
Kata.getMiddle("testing") should return "t"
Kata.getMiddle("middle") should return "dd"
Kata.getMiddle("A") should return "A"
```
**Input**
A word (string) of length **0 < str < 1000** (In javascript you may get slighly more than 1000 in some test cases due to an error in the test cases). You do not need to test for this. This is only here to tell you that you do not need to worry about your solution timing out.
**Output**
The middle character(s) of the word represented as a string.
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Strings
- Link: [Get the Middle Character](https://www.codewars.com/kata/56747fd5cb988479af000028)
### 14. Multiples of 3 or 5
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Finish the solution so that it returns the sum of all the multiples of 3 or 5 **below** the number passed in.
Additionally, if the number is negative, return 0.
**Note:** If the number is a multiple of both 3 and 5, only count it once.
- Difficulty: _6 kyu_
- Tags:
- Mathematics
- Algorithms
- Link: [Multiples of 3 or 5](https://www.codewars.com/kata/514b92a657cdc65150000006)
### 15. Stop gninipS My sdroW!
Write a function that takes in a string of one or more words, and return the same string, but with all words that have five or more letters reversed (Just like the name of this Kata). Strings passed in will consist of only letters and spaces, Spaces will be included only when more than word is present.
Examples:
```javascript
"Hey fellow warriors" --> "Hey wollef sroirraw"
"This is a test --> "This is a test"
"This is another test" --> "This is rehtona test"
```
- Difficulty: _6 kyu_
- Tags:
- Strings
- Algorithms
- Link: [Stop gninipS My sdroW!](https://www.codewars.com/kata/5264d2b162488dc400000001)
### 16. Find the odd int
Given an array of integers, find the one that appears an odd number of times.
There will always be only one integer that appears an odd number of times.
**Examples**
**[7]** should return **7**, because it occurs 1 time (which is odd)
**[0]** should return **0**, because it occurs 1 time (which is odd)
**[1,1,2]** should return **2**, because it occurs 1 time (which is odd)
**[0,1,0,1,0]** should return **0**, because it occurs 3 time (which is odd)
**[1,2,2,3,3,3,4,3,3,3,2,2,1]** should return **4**, because it occurs 1 time (which is odd)
- Difficulty: _6 kyu_
- Tags:
- Fundamentals
- Link: [Find the odd int](https://www.codewars.com/kata/54da5a58ea159efa38000836)
### 17. Who likes it?
You probably know the "like" system from Facebook and other pages. People can "like" blog posts, pictures or other items. We want to create the text that should be displayed next to such an item.
Implement the function takes an array containing the names of people that like an item. It must return the display text as shown in the examples:
```javascript
[] --> "no one likes this"
["Peter"] --> "Peter likes this"
["Jacob", "Alex"] --> "Jacob and Alex like this"
["Max", "John", "Mark"] --> "Max, John and Mark like this"
["Alex", "Jacob", "Mark", "Max"] --> "Alex, Jacob and 2 others like this"
```
Note: For 4 or more names, the number in **"and 2 others"** simply increases.
- Difficulty: _6 kyu_
- Tags
- Strings
- Fundamentals
- Link: [Who likes it?](https://www.codewars.com/kata/5266876b8f4bf2da9b000362)
### 18. Sum of Digits / Digital Root
Digital root is the recursive sum of all the digits in a number.
Given **n**, take the sum of the digits of **n**. If that value has more than one digit, continue reducing in this way until a single-digit number is produced. The input will be a non-negative integer.
**Examples**
```javascript
16 --> 1 + 6 = 7
942 --> 9 + 4 + 2 = 15 --> 1 + 5 = 6
132189 --> 1 + 3 + 2 + 1 + 8 + 9 = 24 --> 2 + 4 = 6
493193 --> 4 + 9 + 3 + 1 + 9 + 3 = 29 --> 2 + 9 = 11 --> 1 + 1 = 2
```
- Difficutly: _6 kyu_
- Tags:
- Mathematics
- Algorithms
- Link: [Sum of Digits / Digital Root](https://codewars.com/kata/541c8630095125aba6000c00)
### 19. Array.diff
Your goal in this kata is to implement a difference function, which subtracts one list from another and returns the result.
It should remove all values from list **a**, which are present in list **b** keeping their order.
```javascript
arrayDiff([1, 2], [1]) == [2];
```
If a value is present in **b**, all of its occurrences must be removed from the other:
```javascript
arrayDiff([1, 2, 2, 2, 3], [2]) == [1, 3];
```
- Difficulty: _6 kyu_
- Tags:
- Arrays
- Fundamentals
- Algorithms
- Link: [Array.diff](https://www.codewars.com/kata/523f5d21c841566fde000009)
### 20. Create Phone Number
Write a function that accepts an array of 10 integers (between 0 and 9), that returns a string of those numbers in the form of a phone number.
**Example**
```javascript
createPhoneNumber([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]); // => returns "(123) 456-7890"
```
The returned format must be correct in order to complete this challenge.
Don't forget the space after the closing parentheses!
- Difficulty: _6 kyu_
- Tags:
- Arrays
- Strings
- Regular Expressions
- Algorithms
- Link: [Create Phone Number](https://www.codewars.com/kata/525f50e3b73515a6db000b83)
### 21. Find The Parity Outlier
Your are given an array (which will have a length of at least 3, but could be very large) containing integers. The array is either entirely comprised of odd integers or entirely comprised of even integeres except for a single integer **N**. Write a method that takes the array as an argument and returns this "outlier" **N**.
**Examples**
```javascript
[2, 4, 0, 100, 4, 11, 2602, 36] --> 11 (the only odd number)
[160, 3, 1719, 19, 11, 13, -21] --> 160 (the only even number)
```
- Difficulty: _6 kyu_
- Tags:
- Algorithms
- Link: [Find The Parity Outlier](https://www.codewars.com/kata/5526fc09a1bbd946250002dc)
### 22. Counting Duplicates
**Count the number of Diplicates**
Write a function that will return the count of **distinct case-insensitive** alphabetic characters and numeric digits that occur more than once in the input string. The input string can be assumed to contain only alphabets (both uppercase and lowercase) and numeric digits.
**Example**
"abcde" -> 0 **# no characters repeats more than once**
"aabbcde" -> 2 **# 'a' and 'b'**
"aabBcde" -> 2 **# 'a' occurs twice and 'b' twice (`b` and `B`)**
"indivisibility" -> 1 **# 'i' occurs six times**
"Indivisibilities" -> 2 **# 'i' occurs seven times** and 's' occurs twice
"aA11" -> 2 **# 'a' and '1'**
"ABBA" -> 2 **# 'A' and 'B' each occur twice**
- Difficulty: _6 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Count the number of Duplicates](https://www.codewars.com/kata/54bf1c2cd5b56cc47f0007a1)
### 23. Duplicate Encoder
The goal of this exercise is to convert a string to a new string where each character in the new string is **"("** if that character appears only once in the original string, or **")"** if that character appears more than once in the original string. Ignore capitalization when determining if a character is a duplicate.
**Example**
```javascript
"din" => "((("
"recede" => "()()()"
"Success" => ")())())"
"(( @" => "))(("
```
**Notes**
Assertion messages may be unclear about what they display in some languages. If you read **"...It Should encode XXX"**, the **"XXX"** is the expected result, not the input!
- Difficulty: _6 kyu_
- Tags:
- Strings
- Arrays
- Fundamentals
- Link: [Duplicate Encode](https://www.codewars.com/kata/54b42f9314d9229fd6000d9c)
### 24. List Filtering
In this kata you will create a function that takes a list of non-negative integers and strings and returns a new list with the strings filtered out.
**Example**
```javascript
filter_list([1, 2, "a", "b"]) == [1, 2];
filter_list([1, "a", "b", 0, 15]) == [1, 0, 15];
filter_list([1, 2, "aasf", "1", "123", 123]) == [1, 2, 123];
```
- Difficulty: _7 kyu_
- Tags:
- Lists
- Filtering
- Data Structures
- Fundamentals
- Link: [ListFiltering](https://www.codewars.com/kata/53dbd5315a3c69eed20002dd)
### 25. Mumbling
This time no story, no theory. The examples below show you how to write function **accum** :
**Examples:**
```javascript
accum("abcd") -> "A-Bb-Ccc-Dddd"
accum("RqaEzty") -> "R-Qq-Aaa-Eeee-Zzzzz-Tttttt-Yyyyyyy"
accum("cwAt") -> "C-Ww-Aaa-Tttt"
```
The parameter of accum is a string which includes only letters from **a..z** and **A..Z**.
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Strings
- Puzzles
- Link: [Mumbling](https://www.codewars.com/kata/5667e8f4e3f572a8f2000039)
### 26. You're a square!
**A square of squares**
You like building blocks. You especially like building blocks that are squares. And what you even like more, is to arrange them into a square of square building blocks!
However, sometimes, you can't arrange them into a square. Instead, you end up with an ordinary rectangle! Those blasted things! If you just had a way to know, whether you're currently working in vain… Wait! That's it! You just have to check if your number of building blocks is a perfect square.
**Task**
Given an integral number, determine if it's a square number:
_"In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself."_
The tests will always use some integral number, so don't worry about that in dynamic typed languages.
**Examples**
```javascript
-1 => false
0 => true
3 => false
4 => true
25 => true
26 => false
```
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Mathematics
- Link: [You're a square!](https://www.codewars.com/kata/54c27a33fb7da0db0100040e)
### 27. Isograms
An isogram is a word that has no repeating letters, consecutive or non-consecutive. Implement a function that determines whether a string that contains only letters is an isogram. Assume the empty string is an isogram. Ignore letter case.
**Example: (Input-->Ouput)**
"Dermatoglyphics" --> true "aba" --> false "moOse" --> false (ignore letter case)
```javascript
isIsogram "Dermatoglyphics" = true
isIsogram "moose" = false
isIsogram "aba" = false
```
- Difficulty: _7 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Isogram](https://www.codewars.com/kata/54ba84be607a92aa900000f1)
### 28. Exes and Ohs
Check to see if a string has the same amount of 'x's and 'o's. The method must return a boolean and be case insensitive. The string can contain any char.
Examples input/output:
```javascript
XO("ooxx") => true
XO("xooxx") => false
XO("ooxXm") => true
XO("zpzpzpp") => true // when no 'x' and 'o' is present should return true
XO("zzoo") => false
```
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Exes and Ohs](https://www.codewars.com/kata/55908aad6620c066bc00002a)
### 29. Shortest Word
Simple, given a string of words, return the length of the shortest word(s).
String will never be empty and you do not need to account for different data types.
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Shortest Word](https://www.codewars.com/kata/57cebe1dc6fdc20c57000ac9)
### 30. Replace With Alphabet Position
Welcome.
In this kata you are required to, given a string, replace every letter with its position in the alphabet.
If anything in the text isn't a letter, ignore it and don't return it.
**"a" = 1**, **"b" = 2**, etc.
**Example**
```javascript
alphabetPosition("The sunset sets at twelve o' clock.");
```
Should return **"20 8 5 19 21 14 19 5 20 19 5 20 19 1 20 20 23 5 12 22 5 15 3 12 15 3 11"** ( as a string )
- Difficulty: _6 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Replace With Alphabet Position](https://www.codewars.com/kata/546f922b54af40e1e90001da)
### 31. Presistent Bugger.
Write a function, **persistence**, that takes in a positive parameter **num** and returns its multiplicative persistence, which is the number of times you must multiply the digits in **num** until you reach a single digit.
For example **(Input-->Output)**:
```javascript
39 --> 3 (because 3*9 = 27, 2*7 = 14, 1*4 = 4 and 4 has only one digit)
999 --> 4 (because 9*9*9 = 729, 7*2*9 = 126, 1*2*6 = 12, and finally 1*2 = 2)
4 --> 0 (because 4 is already a one-digit number)
```
- Difficulty: _6 kyu_
- Tags:
- Fundamentals
- Link: [Presistent Bugger.](https://www.codewars.com/kata/55bf01e5a717a0d57e0000ec)
### 32. Credit Card Mask
Usually when you buy something, you're asked whether your credit card number, phone number or answer to your most secret question is still correct. However, since someone could look over your shoulder, you don't want that shown on your screen. Instead, we mask it.
Your task is to write a function **maskify**, which changes all but the last four characters into **'#'**.
\*\*Examples (input-->output):
```javascript
"4556364607935616" --> "############5616"
"64607935616" --> "#######5616"
"1" --> "1"
"" --> ""
// "What was the name of your first pet?"
"Skippy" --> "##ippy"
"Nananananananananananananananana Batman!" --> "####################################man!"
```
- Difficulty: _7 kyu_
- Tags:
- Strings
- Algorithms
- Link: [Credit Card Mask](https://www.codewars.com/kata/5412509bd436bd33920011bc)
### 33. Sum of two lowest positive integers
Create a function that returns the sum of the two lowest positive numbers given an array of minimum 4 positive integers. No floats or non-positive integers will be passed.
For example, when an array is passed like **[19, 5, 42, 2, 77]**, the output should be **7**.
**[10, 343445353, 3453445, 3453545353453]** should return **3453455**.
- Difficulty: _7 kyu_
- Tags:
- Arrays
- Fundamentals
- Link: [Sum of two lowest positive integers](https://www.codewars.com/kata/558fc85d8fd1938afb000014)
### 34. String ends with?
Complete the solution so that it returns true if the first argument(string) passed in ends with the 2nd argument (also a string).
Examples:
```javascript
solution("abc", "bc"); // returns true
solution("abc", "d"); // returns false
```
- Difficulty: _7 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [String ends with?](https://www.codewars.com/kata/51f2d1cafc9c0f745c00037d)
### 35. Bit Counting
Write a function that takes an integer as input, and returns the number of bits that are equal to one in the binary representation of that number. You can guarantee that input is non-negative.
_Example_: The binary representation of 1234 is 10011010010, so the function should return 5 in this case
- Difficulty: _6 kyu_
- Tags:
- Bits
- Algorithms
- Link: [Bit Counting](https://www.codewars.com/kata/526571aae218b8ee490006f4)
### 36. Opposite number
Very simple, given a number (integer / decimal / both depending on the language), find its opposite (additive inverse).
Examples:
```javascript
1: -1
14: -14
-34: 34
```
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Link: [opposite number](https://www.codewars.com/kata/56dec885c54a926dcd001095)
### 37. Remove First and Last Character
It's pretty straightforward. Your goal is to create a function that removes the first and last characters of a string. You're given one parameter, the original string. You don't have to worry about strings with less than two characters.
- Difficulty: _8 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Remove First and Last Character](https://www.codewars.com/kata/56bc28ad5bdaeb48760009b0)
### 38. Take a Ten Minutes Walk
You live in the city of Cartesia where all roads are laid out in a perfect grid. You arrived ten minutes too early to an appointment, so you decided to take the opportunity to go for a short walk. The city provides its citizens with a Walk Generating App on their phones -- everytime you press the button it sends you an array of one-letter strings representing directions to walk (eg. ['n', 's', 'w', 'e']). You always walk only a single block for each letter (direction) and you know it takes you one minute to traverse one city block, so create a function that will return true if the walk the app gives you will take you exactly ten minutes (you don't want to be early or late!) and will, of course, return you to your starting point. Return false otherwise.
_"Note: you will always receive a valid array containing a random assortment of direction letters ('n', 's', 'e', or 'w' only). It will never give you an empty array (that's not a walk, that's standing still!)."_
- Difficulty: _6 kyu_
- Tags:
- Arrays
- Fundamentals
- Link: [Take a Ten Minutes Walk](https://www.codewars.com/kata/54da539698b8a2ad76000228)
### 39. Square(n) Sum
Complete the square sum function so that it squares each number passed into it and then sums the results together.
For example, for **[1, 2, 2]** it should return **9** because 1^2 + 2^2 + 2^2 = 9.
- Difficulty: _8 kyu_
- Tags:
- Arrays
- Lists
- Fundamentals
- Link: [Square(n) Sum](https://www.codewars.com/kata/515e271a311df0350d00000f)
### 40. String repeat
Write a function that accepts an integer **n** and a string **s** as parameters, and returns a string of **s** repeated exactly **n** times.
**Examples (input->output)**
```javascript
6, "I" -> "IIIIII"
5, "Hello" -> "HelloHelloHelloHelloHello"
```
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Strings
- Link: [String repeat](https://www.codewars.com/kata/57a0e5c372292dd76d000d7e)
### 41. Complementary DNA
Deoxyribonucleic acid (DNA) is a chemical found in the nucleus of cells and carries the "instructions" for the development and functioning of living organisms.
If you want to know more: http://en.wikipedia.org/wiki/DNA
In DNA strings, symbols "A" and "T" are complements of each other, as "C" and "G". Your function receives one side of the DNA (string, except for Haskell); you need to return the other complementary side. DNA strand is never empty or there is no DNA at all (again, except for Haskell).
More similar exercise are found here: http://rosalind.info/problems/list-view/ (source)
Example: (**input --> output**)
```javascript
"ATTGC" --> "TAACG"
"GTAT" --> "CATA"
```
- Difficulty: _7 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Complementary DNA](https://www.codewars.com/kata/554e4a2f232cdd87d9000038)
### 42. Grasshopper - Summation
**Summation**
Write a program that finds the summation of every number from 1 to num. The number will always be a positive integer greater than 0. Your function only needs to return the result, what is shown between parentheses in the example below is how you reach that result and it's not part of it, see the sample tests.
For example (**Input -> Output**):
```javascript
2 -> 3 (1 + 2)
8 -> 36 (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8)
```
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Mathematics
- Link: [Grasshopper - Summation](https://www.codewars.com/kata/55d24f55d7dd296eb9000030)
### 43. Remove String Spaces
Write a function that removes the spaces from the string, then return the resultant string.
Examples:
```javascript
Input -> Output
"8 j 8 mBliB8g imjB8B8 jl B" -> "8j8mBliB8gimjB8B8jlB"
"8 8 Bi fk8h B 8 BB8B B B B888 c hl8 BhB fd" -> "88Bifk8hB8BB8BBBB888chl8BhBfd"
"8aaaaa dddd r " -> "8aaaaaddddr"
```
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Strings
- Link: [Remove String Spaces](https://www.codewars.com/kata/57eae20f5500ad98e50002c5)
### 44. Find the smallest integer in the array
Given an array of integers your solution should find the smallest integer.
For example:
- Given **[34, 15, 88, 2]** your solution will return **2**
- Given **[34, -345, -1, 100]** your solution will return **-345**
You can assume, for the purpose of this kata, that the supplied array will not be empty.
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Link: [Find the smallest integer in the array](https://www.codewars.com/kata/55a2d7ebe362935a210000b2)
### 45. Counting sheep...
Consider an array/list of sheep where some sheep may be missing from their place. We need a function that counts the number of sheep present in the array (true means present).
For example,
```javascript
[
true,
true,
true,
false,
true,
true,
true,
true,
true,
false,
true,
false,
true,
false,
false,
true,
true,
true,
true,
true,
false,
false,
true,
true,
];
```
The correct answer would be **17**.
Hint: Don't forget to check for bad values like **null/undefined**
- Difficulty: _8 kyu_
- Tags:
- Arrays
- Fundamentals
- Link: [Counting sheep...](https://www.codewars.com/kata/54edbc7200b811e956000556)
### 46. Two to One
Take 2 strings **s1** and **s2** including only letters from **a** to **z**. Return a new sorted string, the longest possible, containing distinct letters - each taken only once - coming from s1 or s2.
**Examples:**
```javascript
a = "xyaabbbccccdefww"
b = "xxxxyyyyabklmopq"
longest(a, b) -> "abcdefklmopqwxy"
a = "abcdefghijklmnopqrstuvwxyz"
longest(a, a) -> "abcdefghijklmnopqrstuvwxyz"
```
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Two to One](https://www.codewars.com/kata/5656b6906de340bd1b0000ac)
### 47. Friend or Foe?
Make a program that filters a list of strings and returns a list with only your friends name in it.
If a name has exactly 4 letters in it, you can be sure that it has to be a friend of yours! Otherwise, you can be sure he's not...
Ex: Input = ["Ryan", "Kieran", "Jason", "Yous"], Output = ["Ryan", "Yous"]
i.e.
```javascript
friend[("Ryan", "Kieran", "Mark")]`shouldBe`[("Ryan", "Mark")];
```
Note: keep the original order of the names in the output.
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Friend or Foe?](https://www.codewars.com/kata/55b42574ff091733d900002f)
### 48. Categorize New Member
The Western Suburbs Croquet Club has two categories of membership, Senior and Open. They would like your help with an application form that will tell prospective members which category they will be placed.
To be a senior, a member must be at least 55 years old and have a handicap greater than 7. In this croquet club, handicaps range from -2 to +26; the better the player the lower the handicap.
**Input**
Input will consist of a list of pairs. Each pair contains information for a single potential member. Information consists of an integer for the person's age and an integer for the person's handicap.
**Output**
Output will consist of a list of string values (in Haskell and C: Open or Senior) stating whether the respective member is to be placed in the senior or open category.
**Example**
```javascript
input = [
[18, 20],
[45, 2],
[61, 12],
[37, 6],
[21, 21],
[78, 9],
];
output = ["Open", "Open", "Senior", "Open", "Open", "Senior"];
```
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Categorize New Member](https://www.codewars.com/kata/5502c9e7b3216ec63c0001aa)
### 49. Basic Mathematical Operations
Your task is to create a function that does four basic mathematical operations.
The function should take three arguments - operation(string/char), value1(number), value2(number).
The function should return result of numbers after applying the chosen operation.
**Examples(Operator, value1, value2) --> output**
```javascript
('+', 4, 7) --> 11
('-', 15, 18) --> -3
('*', 5, 5) --> 25
('/', 49, 7) --> 7
```
- Difficulty: _7 kyu_
- Tags:
- Mathematics
- Fundamentals
- Link: [Basic Mathematical Operations](https://www.codewars.com/kata/57356c55867b9b7a60000bd7)
### 50. Convert a String to a Number!
We need a function that can transform a string into a number. What ways of achieving this do you know?
Note: Don't worry, all inputs will be strings, and every string is a perfectly valid representation of an integral number.
**Examples**
```javascript
"1234" --> 1234
"605" --> 605
"1405" --> 1405
"-7" --> -7
```
- Difficulty: _8 kyu_
- Tags:
- Parsing
- Strings
- Fundamentals
- Link: [Convert a String to a Number!](https://www.codewars.com/kata/544675c6f971f7399a000e79)
### 51. Beginner Series #3 Sum of Numbers
Given two integers **a** and **b**, which can be positive or negative, find the sum of all the integers between and including them and return it. If the two numbers are equal return **a** or **b**.
**Note**: **a** and **b** are not ordered!
**Examples (a, b) --> output (explanation)**
```javascript
(1, 0) --> 1 (1 + 0 = 1)
(1, 2) --> 3 (1 + 2 = 3)
(0, 1) --> 1 (0 + 1 = 1)
(1, 1) --> 1 (1 since both are same)
(-1, 0) --> -1 (-1 + 0 = -1)
(-1, 2) --> 2 (-1 + 0 + 1 + 2 = 2)
```
Your function should only return a number, not the explanation about how you get that number.
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Algorithms
- Link: [Beginner Series #3 Sum of Numbers](https://www.codewars.com/kata/55f2b110f61eb01779000053)
### 52. Your order, please
Your task is to sort a given string. Each word in the string will contain a single number. This number is the position the word should have in the result.
Note: Numbers can be from 1 to 9. So 1 will be the first word (not 0).
If the input string is empty, return an empty string. The words in the input String will only contain valid consecutive numbers.
**Examples**
```javascript
"is2 Thi1s T4est 3a" --> "Thi1s is2 3a T4est"
"4of Fo1r pe6ople g3ood th5e the2" --> "Fo1r the2 g3ood 4of th5e pe6ople"
"" --> ""
```
- Difficulty: _6 kyu_
- Tags:
- Strings
- Fundamentals
- Link: [Your order, please](https://www.codewars.com/kata/55c45be3b2079eccff00010f)
### 53. Printer Error
In a factory a printer prints labels for boxes. For one kind of boxes the printer has to use colors which, for the sake of simplicity, are named with letters from **a to m**.
The colors used by the printer are recorded in a control string. For example a "good" control string would be **aaabbbbhaijjjm** meaning that the printer used three times color a, four times color b, one time color h then one time color a...
Sometimes there are problems: lack of colors, technical malfunction and a "bad" control string is produced e.g. **aaaxbbbbyyhwawiwjjjwwm** with letters not from **a to m**.
You have to write a function **printer_error** which given a string will return the error rate of the printer as a string representing a rational whose numerator is the number of errors and the denominator the length of the control string. Don't reduce this fraction to a simpler expression.
The string has a length greater or equal to one and contains only letters from **a** to **z**.
**Examples:**
```javascript
s="aaabbbbhaijjjm"
printer_error(s) => "0/14"
s="aaaxbbbbyyhwawiwjjjwwm"
printer_error(s) => "8/22"
```
- Difficulty: _7 kyu_
- Tags:
- Fundamentals
- Link: [Printer Error](https://www.codewars.com/kata
/56541980fa08ab47a0000040)
### 54. Century From Year
**Introduction**
The first century spans from the year 1 up to and including the year 100, the second century - from the year 101 up to and including the year 200, etc.
**Task**
Given a year, return the century it is in.
**Examples**
```javascript
1705 --> 18
1900 --> 19
1601 --> 17
2000 --> 20
2742 --> 28
```
- Difficulty: _8 kyu_
- Tags:
- Fundamentals
- Mathematics
- Link: [Century From Year](https://www.codewars.com/kata/5a3fe3dde1ce0e8ed6000097)
### 55. Keep Hydrated!
Nathan loves cycling.
Because Nathan knows it is important to stay hydrated, he drinks 0.5 litres of water per hour of cycling.
You get given the time in hours and you need to return the number of litres Nathan will drink, rounded to the smallest value.
For example:
```javascript
time = 3 ----> litres = 1
time = 6.7---> litres = 3
time = 11.8--> litres = 5
```
- Difficulty: _8 kyu_
- Tags:
- Algorithms
- Mathematics
- Fundamentals
- Link: [Keep Hydrated!](https://www.codewars.com/kata/582cb0224e56e068d800003c)