Override offer.apply method for each offer type

.gitignore

@@ -1,3 +1,4 @@
 .idea/vcs.xml
 .idea/workspace.xml
+.idea/misc.xml
 out

src/checkout/AnyGoodsOffer.java

@@ -11,6 +11,7 @@ public AnyGoodsOffer(int totalCost, int points) {
 
     @Override
     public void apply(Check check) {
-
+        if (this.totalCost <= check.getTotalCost())
+            check.addPoints(this.points);
     }
 }

src/checkout/CheckoutService.java

@@ -23,16 +23,5 @@ public Check closeCheck() {
 
     public void useOffer(Offer offer) {
         offer.apply(check);
-        if (offer instanceof FactorByCategoryOffer) {
-            FactorByCategoryOffer fbOffer = (FactorByCategoryOffer) offer;
-            int points = check.getCostByCategory(fbOffer.category);
-            check.addPoints(points * (fbOffer.factor - 1));
-        } else {
-            if (offer instanceof AnyGoodsOffer) {
-                AnyGoodsOffer agOffer = (AnyGoodsOffer) offer;
-                if (agOffer.totalCost <= check.getTotalCost())
-                    check.addPoints(agOffer.points);
-            }
-        }
     }
 }

src/checkout/FactorByCategoryOffer.java

@@ -11,6 +11,7 @@ public FactorByCategoryOffer(Category category, int factor) {
 
     @Override
     public void apply(Check check) {
-
+        int points = check.getCostByCategory(this.category);
+        check.addPoints(points * (this.factor - 1));
     }
 }