Coding Challenge Guidelines

• You can choose any programming language (we’d suggest choosing your strongest)
• You can use the internet, but please don’t look up or copy an existing solution—we want to see how you work
• This isn’t a race, but please track your time so you can tell us how long it took you
• Please don’t spend any longer than 90 minutes total

Evaluation Criteria

Write a library for generating random PIN codes. You probably know what a PIN code is; it’s a short sequence of numbers, often used as a passcode for bank cards.

• The library should export a function that returns a batch of 1,000 PIN codes in random order
• Each PIN code in the batch should be unique
• Each PIN should be:
• 4 digits long
• Two consecutive digits should not be the same (e.g. 1156 is invalid)
• Three consecutive digits should not be incremental (e.g. 1236 is invalid)
• The library should have automated tests.

Technologies

• Typescript
• Jest
• Microbundle
• ESLint
• Prettier

Setup

1. Install dependencies

npm install

#or

yarn install

Run tests

npm run test

#or

yarn test

Install the library

npm install pin-generator-1-cazaph

#or

yarn add pin-generator-1-cazaph

https://www.npmjs.com/package/pin-generator-1-cazaph

Usage

Generate a batch of 1,000 PIN codes in random order

import {generatePins, isValidPin} from "pin-generator-1-cazaph";

const pins = generatePins();
console.log(pins);
// ['pin1', 'pin2', 'pin3', ...]

console.log(isValidPin("7801")); // true
console.log(isValidPin("1236")); // false
console.log(isValidPin("1156")); // false
console.log(isValidPin("0023")); // false
console.log(isValidPin("1199")); // false

API

generatePins(count?: number): string[]

This function allows you to generate random pins according to the count. The count is optional and defaults to 1,000.

isValidPin(pin: string, pins?:[]): boolean

This function validates if the pin is valid. To be valid the pin should:

• Have 4 digits long,
• Not contain consecutive digits
• Not contain digits that are incrementally increasing.
• Not be included in the pins array.

The pins parameter is optional and defaults to an empty array.

hasSameConsecutiveDigits(numbers: number[]): boolean

This function checks if the numbers has consecutive digits.

isIncremental(numbers: number[]): boolean

This function checks if the numbers contains 3 more numbers incrementally increasing. e.g. 1239

shuffle(arr: any[]): any[]

This function takes a list of numbers and returns a shuffled version of the same list.

License

The MIT License (MIT). Please see License File for more information.