EcmaChallenge

A series of challenges in ECMA Script 2015 for @sumanita.

1. Arrays

An initial familiarisation challenge to build up knowledge of the Git and unit-testing approach.

Given an array of ints, output an array of squares.

For example:

[1, 2, 3, 4, 5] -> [1, 4, 9, 16, 25]
[5, 2, 9] -> [25, 4, 81]
[] -> []
null -> <<throws an Error()>>

How-to

To get started, run:

> git clone https://github.com/a2wd/EcmaChallenge.git

To finish the first challenge, first change directory to the arrays challenge, then run npm to get the mocha (unit-testing) dependency:

> cd EcmaChallenge\1.Arrays
> npm install

Use app.js to write your code, while in development you can use console.log or the node-inspector package to check your work.

When you are done, use the npm test command:

npm test

This will let you know if your code passes or if it needs more work.

2. Recursion

A warm-up exercise to invert a binary tree. A classic of interview-type questions.

You are given a data structure, Node and must correctly code an inversion function. You are able to code in a loop or with recursion, though recursion is considerably more elegant.

The Node object has three properties:

• value - the value of that particular node
• left - a left branch to be initialised to a Node() object
• right - right branch to be initialised to a Node() object

Given a binary tree (left), the function will return the output (right):

                   1                                                1
                   |                                                |
        2----------+---------3                           3----------+---------2
        |                    |            +---->         |                    |
   4----+---5            6---+-------7    +---->    7----+---6            5---+-------4
   |                                                                                  |
8--+--9                                                                            9--+-8