Update to list based lookup

src/engine/gameManager/BuildingManager.java

@@ -56,15 +56,11 @@ public enum BuildingManager {
         if (building.hirelings.isEmpty())
             return 0;
 
-        for (int i = 0; i < numOfSlots; i++) {
+        if (building.hirelings.size() == numOfSlots)
+            return -1;
 
-            if (i > building.hirelings.size())
-                return i;
+        return building.hirelings.size() + 1;
 
-            if (building.hirelings.get(i) == null)
-                return i;
-        }
-        return -1;
     }
 
     public static int getLastAvailableSlot(Building building) {
@@ -82,15 +78,10 @@ public enum BuildingManager {
         if (building.hirelings.isEmpty())
             return numOfSlots - 1;
 
-        for (int i = numOfSlots - 1; i >= 0; i--) {
-
-            if (i > building.hirelings.size())
-                return i;
+        if (building.hirelings.size() == numOfSlots)
+            return -1;
 
-            if (building.hirelings.get(i) == null)
-                return i;
-        }
-        return -1;
+        return numOfSlots - 1;
     }
 
     public static BuildingLocation getSlotLocation(Building building, int slot) {