feat(FishCalculator): add first iteration of recursion

src/main/java/fish_variety/FishCalculator.java

@@ -0,0 +1,37 @@
+package fish_variety;
+
+import java.util.ArrayList;
+
+public class FishCalculator {
+
+    public static FishCollection mostCompatibleFishTypesOfCollection(int price, FishCollection initialCollection) {
+        FishConstraints constraints = initialCollection.getConstraints();
+
+        ArrayList<FishCollection> variants = new ArrayList<>();
+
+        for (Fish fish : constraints.getAllFish()) {
+            FishCollection collectionVariant = new FishCollection(constraints, initialCollection.getFishes());
+
+            collectionVariant.add(fish);
+
+            if (collectionVariant.isValid() && collectionVariant.getPrice() <= price) {
+                variants.add(FishCalculator.mostCompatibleFishTypesOfCollection(price, collectionVariant));
+            }
+        }
+
+        if (variants.size() == 0) {
+            return initialCollection;
+        }
+
+        // Get largets collection in variants
+        FishCollection largestCollectionVariant = variants.get(0);
+
+        for (FishCollection fishCollection : variants) {
+            if (fishCollection.getFishes().size() > largestCollectionVariant.getFishes().size()) {
+                largestCollectionVariant = fishCollection;
+            }
+        }
+
+        return largestCollectionVariant;
+    }
+}

src/main/java/fish_variety/Main.java

@@ -53,6 +53,7 @@ public static void main( String[] args )
             grueneMigraene, prachtpiranha, zitterling
         });
 
-        FishCollection collection = new FishCollection(constraints);
+        FishCollection bestVariant = FishCalculator.mostCompatibleFishTypesOfCollection(170, new FishCollection(constraints));
+        System.out.println(bestVariant);
     }
 }