Question

Given an amount in ml and 3 pack sizes (20ml, 200ml and 1000ml) I’d like to calculate how many of each packs are needed to fulfill the total amount.

E.g.

Amount = 3210ml
1000ml = 3 packs
200ml = 1 pack
20ml = 1 pack (always round up to nearest quantity)

This is pretty much just like a change calculator, and I’m looking for the right way to do it.

Here’s my attempt

public class PackSizeCalculator
{
    private const int LargePackSize = 1000;
    private const int MediumPackSize = 200;
    private const int SmallPackSize = 20;

    public int LargePacks {get; set;}
    public int MediumPacks {get; set;}
    public int SmallPacks {get; set;}

    public  PackSizeCalculator(int amount)
    {
        int remainder = amount;

        while(remainder > 0) {
            if(remainder >= LargePackSize)
            {
                LargePacks = remainder / LargePackSize;
                remainder = remainder % LargePackSize;
            }
            else if(remainder >= MediumPackSize)
            {
                MediumPacks = remainder / MediumPackSize;
                remainder = remainder % MediumPackSize;
            }
            else if(remainder > SmallPackSize)
            {
                if(remainder % SmallPackSize == 0)
                {
                    SmallPacks = (remainder / SmallPackSize);
                }
                else {
                    SmallPacks = (remainder / SmallPackSize) + 1;
                }
                remainder = 0;
            }
            else {
                SmallPacks = 1;
                remainder = 0;
            }
        }
    }
}

Is this a good way to go about it or would you recommend something different?

Answer 1

Something like this:

const int LARGE_PACK = 1000;
const int MEDIUM_PACK = 200;
const int SMALL_PACK = 20;

int largePacks = (int)(Amount / LARGE_PACK);
int mediumPacks = (int)((Amount % LARGE_PACK) / MEDIUM_PACK);
int smallPacks = (int)ceil(((float)((Amount % LARGE_PACK) % MEDIUM_PACK) / SMALL_PACK));