Collection of small, interesting programming exercises

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Hey,

This is collection of small, interesting interview practice problems.

Hope you get some utility out of this.

Erik

common-ancestor

Given a binary tree and two nodes A and B from within that tree, write a function to find the node which is the first common ancestor of A and B

find-mode-array

Write a function that finds the mode in an array of numbers.

The mode is the number which occurs the most within a collection.

e.g.

findMode([1, 3, 4, 2, 1, 1, 1] => 1

find-nodes-at-depth-d

Given a binary search tree, write a function that returns a list of all nodes at a certain depth D.

fizzbuzz

Write a function that prints the numbers from 1 to 100. EXCEPT:

* If the number if a multiple of 3, print "Fizz" instead of the number
* If the number is a multiple of 5, print "Buzz" instead of the number
* If the number is a multiple of 3 AND 5, print "FizzBuzz" instead of the number

is-anagram

Write a function that determines if two strings are anagrams of eachother.

e.g.

anagram("FOO", "FOO") => true

anagram("FOO", "BAR") => false

anagram("MARY", "ARMY") => true

anagram("MARRY", "ARMY") => false

Hint: Consider what the essential quality is that makes two words anagrams of each other.

k-nearest-neighbors

Given a collection of points on a 2D Cartesian plane (i.e. points with an x and y coordinate where axes intersect at 0), write a function to find the k points nearest to the origin.

merge-sorted-arrays

Write a function that takes as input two sorted arrays of numbers and returns an array which is the combination of the two arrays, also sorted.

e.g.

merge([1, 2, 5, 5, 10], [3, 7, 10, 11]) => [1, 2, 3, 5, 5, 10, 10, 11]

mirror-binary-tree

Write a function to mirror a binary tree.

reverse-string

Write a function that reverses a string.

e.g.

reverse("bicycle") => "elcycib"

While I'm pleased if you're aware of standard library functions to do so, let's pretend they don't exist for the moment and do the work to write it.

Hint: Worth considering is whether your language has immutable strings or not and how that changes how you might answer this question.