Link: http://codekata.com/kata/kata01-supermarket-pricing/
Code kata is a term used to describe a coding exercise that is designed to help programmers improve their skills. The term “kata” comes from martial arts, where it refers to a set of movements that are practiced repeatedly to improve technique. It can help with critical thinking and problem-solving skills. In this post, we will try to understand the problem and the solution for the first kata problem.
Problem
Some items in a supermarket have complex pricing. For example:
- three for a dollar (so what’s the price if I buy 4, or 5?)
- $1.99/pound (so what does 4 ounces cost?)
- Buy two, get one free (so does the third item have a price?)
Let’s think about the following items: 1. does fractional money exist? 2. when (if ever) does rounding take place? 3. how do you keep an audit trail of pricing decisions (and do you need to)? 4. are costs and prices the same class of thing? 5. if a shelf of 100 cans is priced using “buy two, get one free”, how do you value the stock?
Discussion
Q: three for a dollar (so what’s the price if I buy 4, or 5?)
A: Let’s start with the first question. Since three items cost one dollar, the price for one seems to be $1/3. However, this decimal value is not practical in real life. We can round it up. Let’s say the price for one item is x, where x > 1/3. In such case, \(3x\) is larger than $1. Therefore, customer can be incentivized to purchase the 3-for-$1 deal.
TBC