1 files changed, 40 insertions, 5 deletions
diff --git a/Practical2/src/nl/camilstaps/cs/CheckoutHelper.java b/Practical2/src/nl/camilstaps/cs/CheckoutHelper.java
index 5ad7d2d..5688cf0 100644
--- a/Practical2/src/nl/camilstaps/cs/CheckoutHelper.java
+++ b/Practical2/src/nl/camilstaps/cs/CheckoutHelper.java
@@ -12,15 +12,50 @@ class CheckoutHelper {
     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 sum = minimal_price;
-        for (int n : products)
-            sum += n;
-        return sum;
+        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;
+        int has_to_pay = (price / 5) * 5;
         int rest = price % 5;
 
         minimal_price += has_to_pay;