package nl.camilstaps.cs;

import java.util.ArrayList;

/**
 * Created by camil on 11/28/15.
 */
class CheckoutHelper {
    private final ArrayList<Integer> products = new ArrayList<>();
    private int minimal_price;

    public CheckoutHelper() {
    }

    private static int round(int cents) throws IllegalArgumentException {
        switch (cents % 5) {
            case 0: return cents;
            case 1: return cents - 1;
            case 2: return cents - 2;
            case 3: return cents + 2;
            case 4: return cents + 1;
        }
        throw new IllegalArgumentException("Incorrect number of cents.");
    }

    public int minimumPayment(int dividers) {
        int minimums[][] = new int[products.size() + 1][dividers + 1];
        int last[][] = new int[products.size() + 1][dividers + 1];
        for (int p = 0; p <= products.size(); p++) {
            for (int d = 0; d <= dividers; d++) {
                if (p == 0) {
                    minimums[p][d] = 0; // No products
                    last[p][d] = 0;
                } else if (d == 0) {
                    int sum = 0;
                    for (int p2 = 0; p < products.size() && p2 < p; p2++)
                        sum += products.get(p2);
                    minimums[p][d] = round(sum); // no dividers
                    last[p][d] = sum;
                } else {
                    int try1 = minimums[p-1][d] - round(last[p-1][d]) + round(last[p-1][d] + products.get(p-1)); // don't place a divider
                    int try2 = minimums[p-1][d-1] + round(products.get(p-1)); // place a divider
                    if (try1 < try2) {
                        minimums[p][d] = try1;
                        last[p][d] = last[p-1][d] + products.get(p-1);
                    } else {
                        minimums[p][d] = try2;
                        last[p][d] = products.get(p-1);
                    }
                }
            }
        }

        return minimal_price + minimums[products.size()][dividers];
    }

    public void addProduct(int price) {
        int has_to_pay = (price / 5) * 5;
        int rest = price % 5;

        minimal_price += has_to_pay;
        if (rest != 0) {
            products.add(rest);
        }
    }

}