Roll of Coins - Back to all questions
The Challenge
Best suited for: Junior | Senior | Expert Stage: Round 2 | Round 3
At the end of her shift, Amina’s tip jar is full of coins. She needs a little help in counting and stocking her hard earned loot. She wants to organize her coins in rolls so it is easy to bring back to the bank.
Write a program that will help her quickly find out how many rolls she has for each coin denomination and the remainder on each.
Below is a table of how many coins should be in each roll per denomination:
| Coins | Coins per roll | Value |
|---|---|---|
| Penny ==> 1 | 50 | $0.50 |
| Nickel ==> 5 | 40 | $2.00 |
| Dime ==> 10 | 50 | $5.00 |
| Quarter ==> 25 | 40 | $10.00 |
Your program will accept an unsorted array of coins. You can assume that each coin will be either 1, 5, 10 or 25. It should print a message like the one below:
Pennies:10 rolls - 39 left
Nickels: 25 rolls - 0 left
Dimes: 12 rolls - 49 left
Quarter: 2 rolls - 20 left
The context
This one is a slight twist and variation of the Socker Merchant Challenge — Hacker Rank.
It is a frequency count as an exercise and since it can be approached and solved a countless number of ways, it is a perfect pick to get the candidate to walk us through their approach and their iterative process in problem-solving.
I’m a huge proponent of the ‘Make it work first, optimize and refactor later’ approach. I would pay close attention to code that overall is readable and self-documenting.