kyu8_fuel_calculator_total_cost.py

"""
In this kata you will have to write a function that takes litres and price_per_litre (in dollar) as arguments;

Purchases of 2 or more litres get a discount of 5 cents per litre, purchases of 4 or more litres get a discount of
10 cents per litre, and so on every two litres, up to a maximum discount of 25 cents per litre. But total discount per
litre cannot be more than 25 cents. Return the total cost rounded to 2 decimal places. Also you can guess that there
will not be negative or non-numeric inputs;

Good Luck!

Note
    1 Dollar = 100 Cents

https://www.codewars.com/kata/57b58827d2a31c57720012e8

"""


def fuel_price(litres, price_per_litre):
    def __get_discount():
        part = litres // 2
        discount = 5 * part if part <= 4 else 25
        return round(discount / 100, 2)
    
    return round(litres * (price_per_litre - __get_discount()), 2)