/// <summary>
/// Conventional 2-approximation algorithm for 0-1KP
/// Result, r holds to outcome that optimal solution, z* is less than or equal to 2r
/// i.e. 2r provides upper bound for profit
/// </summary>
/// <returns></returns>
public static int Conventional2Approx_KP(List <Item> items, Knapsack knapsack)
{
ItemGroup group = new ItemGroup();
List <Item> sortedItems = UtilFunctions.SortByUnitProfitDescending(items);
// Fill until we reach critical item
foreach (Item item in sortedItems)
{
if (group.TotalWeight() + item.Weight <= knapsack.Capacity)
{
group.AddItem(item);
}
else // we have reached critical item
{
var criticalItem = item;
// 2-approximation solution is one with higher profit value of group or criticalItem
if (criticalItem.Value > group.TotalValue())
{
group = (ItemGroup) new ItemGroup().Add(criticalItem);
}
break;
}
}
return(group.TotalValue());
}
/// <summary>
/// Uses greedy algorithm to get approximation of highest value for profit
/// </summary>
/// <returns></returns>
public static double LPRelaxedApprox_KP(List <Item> items, Knapsack knapsack)
{
ItemGroup group = new ItemGroup();
List <Item> sortedItems = UtilFunctions.SortByUnitProfitDescending(items);
Item criticalItem = new Item("", 0, 0);
double criticalItemFraction = 0;
// Fill until we reach critical item
foreach (Item item in sortedItems)
{
if (group.TotalWeight() + item.Weight <= knapsack.Capacity)
{
group.AddItem(item);
}
else // we have reached critical item
{
criticalItem = item;
criticalItemFraction = (knapsack.Capacity - group.TotalWeight()) / (double)criticalItem.Weight;
break;
}
}
// Add fractional value of next item
double maxProfitValue = group.TotalValue() + criticalItem.Value * criticalItemFraction;
return(maxProfitValue);
}
private void InternalShowItem(int itemId, string itemAssetName, ItemGroup itemGroup, object itemInstance, bool isNewInstance, float duration, object userData)
{
try
{
IItem item = m_ItemHelper.CreateItem(itemInstance, itemGroup, userData);
if (item == null)
{
throw new GameFrameworkException("Can not create item in helper.");
}
ItemInfo itemInfo = ItemInfo.Create(item);
m_ItemInfos.Add(itemId, itemInfo);
itemInfo.Status = ItemStatus.WillInit;
item.OnInit(itemId, itemAssetName, itemGroup, isNewInstance, userData);
itemInfo.Status = ItemStatus.Inited;
itemGroup.AddItem(item);
itemInfo.Status = ItemStatus.WillShow;
item.OnShow(userData);
itemInfo.Status = ItemStatus.Showed;
if (m_ShowItemSuccessEventHandler != null)
{
ShowItemSuccessEventArgs showItemSuccessEventArgs = ShowItemSuccessEventArgs.Create(item, duration, userData);
m_ShowItemSuccessEventHandler(this, showItemSuccessEventArgs);
ReferencePool.Release(showItemSuccessEventArgs);
}
}
catch (Exception exception)
{
if (m_ShowItemFailureEventHandler != null)
{
ShowItemFailureEventArgs showItemFailureEventArgs = ShowItemFailureEventArgs.Create(itemId, itemAssetName, itemGroup.Name, exception.ToString(), userData);
m_ShowItemFailureEventHandler(this, showItemFailureEventArgs);
ReferencePool.Release(showItemFailureEventArgs);
return;
}
throw;
}
}
