In my lab work, I need to create a binary level data structure using a list: Queue and a sub-list: LinkedList.
To implement the structure use built-in types in generalized and ungeneralized implementations (Stack, Stack , Queue, Queue , ArrayList, List , LinkedList). As elements of structures use the following types: (class or struct), which have a key field and information field for sublists (lower level) and a key field for a list (upper level).
The program must perform the following operations:
- initial initialization of the structure (the list is empty).
- adding an item to the list/sublist.
- deleting an element from the list/sublist.
- viewing the first element in the list/sub-list.
- checking the list/sub-list - whether it is empty or not
- displaying the structure on the screen.
The problem is that I don't understand how to create such a two-level data structure. In google I find only how to create a two level data structure using only LinkedList or only Queue, chat gpt also writes a data structure using only one of them, but not both. Could you show an example of implementing such a data structure or just explain how it should work ?
Code chat gpt:
using System;
using System.Collections.Generic;
class Program
{
static void Main()
{
TwoLevelStructure<int, string> structure = new TwoLevelStructure<int, string>();
structure.AddTopLevelElement(1, "TopLevelElement1");
structure.AddTopLevelElement(2, "TopLevelElement2");
structure.AddSublistToTopLevelElement(1, new Queue<string>(new[] { "SublistElement1", "SublistElement2" }));
structure.AddSublistToTopLevelElement(2, new Queue<string>(new[] { "SublistElement3", "SublistElement4" }));
Console.WriteLine("Initial structure:");
structure.DisplayStructure();
Console.WriteLine($"Is structure empty: {structure.IsEmpty()}");
Console.WriteLine($"First element in the structure: {structure.GetFirstElement()}");
structure.RemoveTopLevelElement(1);
Console.WriteLine("Structure after removing an element:");
structure.DisplayStructure();
}
}
class TwoLevelStructure<TKey, TValue>
{
private Dictionary<TKey, Queue<TValue>> topLevelElements;
public TwoLevelStructure()
{
topLevelElements = new Dictionary<TKey, Queue<TValue>>();
}
public void AddTopLevelElement(TKey key, TValue value)
{
topLevelElements.Add(key, new Queue<TValue>(new[] { value }));
}
public void AddSublistToTopLevelElement(TKey key, Queue<TValue> sublist)
{
if (topLevelElements.ContainsKey(key))
{
topLevelElements[key].Enqueue(sublist.Dequeue());
}
}
public void RemoveTopLevelElement(TKey key)
{
topLevelElements.Remove(key);
}
public TValue GetFirstElement()
{
foreach (var queue in topLevelElements.Values)
{
if (queue.Count > 0)
{
return queue.Peek();
}
}
throw new InvalidOperationException("Structure is empty");
}
public bool IsEmpty()
{
return topLevelElements.Count == 0;
}
public void DisplayStructure()
{
foreach (var kvp in topLevelElements)
{
Console.Write($"TopLevelElement {kvp.Key}: ");
foreach (var value in kvp.Value)
{
Console.Write($"{value} ");
}
Console.WriteLine();
}
Console.WriteLine();
}
}
It is not very clear to me what the actual purpose is.
From the method description it sounds fairly similar to a "MultiValueDictionary", I.e. each item is associated with a key, and each key can be associated with multiple values.
You would typically build this around a regular dictionary, for example:
public class MultiValueDictionary<TKey, TValue, TCollection> where TCollection : ICollection<TValue>, new()
{
private readonly IEqualityComparer<TValue> valueComparer;
private Dictionary<TKey, TCollection> dictionary;
public MultiValueDictionary(IEqualityComparer<TKey> keyComparer, IEqualityComparer<TValue> valueComparer)
{
this.valueComparer = valueComparer;
dictionary = new Dictionary<TKey, TCollection>(keyComparer);
}
public void Add(TKey key, TValue value)
{
if (!dictionary.TryGetValue(key, out var collection))
{
collection = new TCollection();
dictionary[key] = collection;
}
collection.Add(value);
}
public bool RemoveFirst(TKey key, TValue value) ...
public bool RemoveAllValuesForKey(TKey key) ...
public IEnumerable<TValue> GetValues(TKey key) ...
public IEnumerable<TKey> GetKeys() ...
public IEnumerable<KeyValuePair<TKey, TValue>> GetKeyValues() ...
}
This lets you specify the collection as a generic argument, i.e. MultiValueDictionary<int, string, List<string>>. I think the ICollection<T> interface is general enough to support all of the listed operations.
However, there is several things in the problem description that makes little sense to me.
use built-in types in generalized and ungeneralized implementations
I assume this means generic and non-generic? I see very little reason to use non-generic collections, so this just seem odd.
(Stack, Stack , Queue, Queue , ArrayList, List , LinkedList)
I assume some of these are intended to be generic, i.e. Stack and Stack<T>. But if the idea is to have a stack of queues, then it just makes very little sense to me for the given operations. It might be useful for some very specialized use case but then you should build a collection for that specific use case, not try to build something reusable. Note that Stack<T> and Queue<T> do not implement ICollection<T>, so are incompatible with the MultiValueDictionary above.
which have a key field and information field for sublists (lower level) and a key field for a list (upper level).
You should typically try to avoid placing restrictions on the type of items that can be stored in a collection. It is usually better to supply any key separately from the item.
Overall the assignment should make the purpose clearer. A dictionary that can store multiple values per key can be useful. But if it intend to do something else the purpose should most stated much more clearly, and I would argue against using a non generic collection, since it will add complexity for little benefit. I would recommend talking to your teacher.