06-whiteboard-code-challenges.md

Whiteboard Code Challenges

1. How could you rewrite the following function to avoid side effects? (make it a "pure" function)

var total = 0;
function sumArrayValues(myarray) {
  for (var i = 0; i < myarray.length; i++) {
    total += myarray[i];
  }
}

2. Write a function that outputs a triangle of asterisks of size n.

// example: `n` of 1 would produce:
*

// example: `n` of 3 would produce:
*
**
***

// example: `n` of 4 would produce:
*
**
***
****

3. Write a function that counts up to 100 but outputs fizz at multiples of 3, buzz at multiples of 5, and fizzbuzz at multiples of both 3 and 5.

4. Write a function that will accept an array and return (not output) a new array in reverse order. (Do not use the built-in .reverse() function)

5. Write a duplicate() function such that duplicate([1,2,3,4,5]); will return [1,2,3,4,5,1,2,3,4,5].

6. Write a function that accepts parameters taxableIncome, taxPaid and returns true if the taxPaid is sufficient to cover the calculated tax liability and false otherwise.

Tax liability is calculated based on taxableIncome as follows: The first $30,000 of taxable income does not increase tax liability, income between $30,000 and $60,000 is taxed at a rate of 20%, income between $60,000 and $100,000 is taxed at a rate of 30%, and income over $100,000 is taxed at a rate of 45%.

For example, a taxableIncome of 70000 would have a tax liability of $9,000 (no liability for the first $30,000 plus $6,000 (20% for the amount between $30k and $60k), plus $3,000 (30% of $10,000 since the last $10,000 falls in the $60k-$100k range))

7. The Fibonacci sequence is a series of numbers starting with 1, 1, 2, 3, 5, 8, 13, … where each number is equal to the two previous numbers added together. Write a function that returns the n-th number in the Fibonacci sequence. e.g. fibonacci(4) will return 3 (the 4th number), fibonacci(7) will return 13 (the 7th number), fibonacci(10) = 55, etc.

8. Write a function that accepts a string and returns a number representing the number of vowels in the string provided.

9. Write a function that accepts a start number and an end number. It should print all the even numbers in the range provided.

10. Write a function that moves the first 2 characters of a string to the end of the string.

11. Write a function that adds all the numbers in a provided array. Bonus: Make all odd numbers count twice.

12. https://codepen.io/chriscoyier/pen/tljap - Reverse the items in a list (in DOM)

13. Rotate a given array to the right by n steps. For example, given [1,2,3,4,5] and 1, you should return [5,1,2,3,4]. Given [1,2,3,4,5] and 8, you should return [3,4,5,1,2].

14. (HARD!) A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ends in the binary representation of N.

For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 265 has binary representation 100001001 and contains two binary gaps: one of length 4 and one of length 2. The number 18 has binary representation 10010 and contains one binary gap of length 1. Note that the outside 0 doesn't count in this case. The number 15 has binary representation 1111 and has no binary gaps.

Write a function that, given a positive integer n, returns the length of its longest binary gap. The function should return 0 if n doesn't contain a binary gap.

For example, given 1049 the function should return 5, because n has binary representation 10000011001 and so its longest binary gap is of length 5.

15. Calculate the total "score" of a provided word. The "score" is calculated by adding 3 points for every consonant and 5 points for every vowel.