balyo-tech-interview

Welcome to the Balyo Tech Interview repository!

Installation

To install Bun runtime, please follow the instructions on the official website.

Alternatively, you can use npx to run Bun without installing it globally:

npx bun <command>

Following instructions assume you have Bun installed globally, adjust the commands accordingly if you are using npx.

To install dependencies:

bun install

To run the tests for a specific exercise, use the following command:

bun test atm/atm1.test.ts # Exercise 1

bun test atm/atm2.test.ts # Exercise 2

Pass --bail flag to stop on first failure (useful for early debugging).

Exercise 1

You must implement the function withdraw (found in src/atm1.ts).

It should return the composition of bills (values and count) an ATM (cash withdrawal machine) will dispense for a given amount.

The function must respect the following specifications:

• The ATM has the following bills: 100, 50, 20, 10, 5.
• The ATM always tries to dispense the minimum number of bills total (it always prefers higher bills).
• The ATM has an predefined amount of bills of each value.
• The ATM may not have the right amount of bills to fulfill the request, in which case it should not leave the user with a partial amount.

Hints

• You don't need to update the internal state of the ATM, as we won't look at it after a withdrawal.
• But, you need to ensure you don't dispense more of a given bill than the ATM has available for that bill (e.g. if the ATM has only 2 bills of 5, the result cannot have 3 bills of 5).

Exercise 2

You must add new features to the withdraw function (found in src/atm2.ts):

• The caller may ask for a preferred bill.
• The ATM will try to respect the preference, dispensing as much as possible of the preferred bill.
• If the ATM does not have enough bills to match the preference, it will dispense the remaining amount following the base specifications of exercise 1.