Done with List&Stack

Added TargetCity and initialized it by the constructor in Sleigh.cs

SantaClausInc/Collections/List.cs

@@ -11,32 +11,44 @@ public sealed class List<TValue>
     /// </summary>
     public const int InitialCapacity = 4;
 
-    // TODO field
+    private const float GrowthFactor = 1.5f; //no need to use double here
+    private TValue[] _data;
 
     /// <summary>
     ///     Creates a new instance of the <see cref="List{TValue}" /> with the <see cref="InitialCapacity" /> capacity
     /// </summary>
     public List()
     {
-        // TODO
+        _data = new TValue[InitialCapacity];
     }
 
     /// <summary>
     ///     Gets the number of items currently stored in the list
     /// </summary>
-    // TODO
+    public int Count { get; private set; }
 
     /// <summary>
     ///     Allows to access and item in the list by its index.
     ///     If an invalid index is supplied the default value for the <see cref="TValue" /> type is returned.
     /// </summary>
     /// <param name="index">Index of the element to access; zero based</param>
-    // TODO
+    public TValue this[int index]
+    {
+        get
+        {
+            if (index < 0 || index > Count)
+            {
+                return default!;
+            }
+
+            return _data[index];
+        }
+    }
 
     /// <summary>
     ///     Gets the current capacity of the list
     /// </summary>
-    // TODO
+    public int Capacity => _data.Length;
 
     /// <summary>
     ///     Adds a new item to the list. Automatically increases capacity of the list if required.
@@ -46,6 +58,19 @@ public sealed class List<TValue>
     /// <param name="value">Value to add to the list</param>
     public void Add(TValue value)
     {
-        // TODO
+        if (Capacity == Count)
+        {
+            Grow();
+        }
+
+        _data[Count++] = value;
+    }
+
+    private void Grow()
+    {
+        var newCapacity = Math.Round(Capacity * GrowthFactor);
+        var newData = new TValue[(int)newCapacity];
+        Array.Copy(_data, newData, Count);
+        _data = newData;
     }
 }

SantaClausInc/Collections/Node.cs

@@ -0,0 +1,7 @@
+namespace SantaClausInc.Collections;
+
+public sealed class Node<TValue>(TValue? value)
+{
+    public TValue? Data { get; } = value;
+    public Node<TValue>? Next { get; set; }
+}

SantaClausInc/Collections/Stack.cs

@@ -8,24 +8,24 @@ namespace SantaClausInc.Collections;
 /// <typeparam name="TValue">Type of the values stored in the stack</typeparam>
 public sealed class Stack<TValue>
 {
-    // TODO _head field
+    private Node<TValue>? _head;
 
     /// <summary>
     ///     Creates a new instance of the <see cref="Stack{TValue}" />
     /// </summary>
     public Stack()
     {
-        // TODO
+        _head = null;
     }
 
     /// <summary>
     ///     Gets the number of items on the stack
     /// </summary>
-    // TODO
+    public int Count { get; private set; }
 
     // uncomment this once the fields are implemented to avoid redundant nullability warnings
-    //[MemberNotNullWhen(false, nameof(_head))]
-    private bool IsEmpty => false; // TODO actual implementation
+    [MemberNotNullWhen(false, nameof(_head))]
+    private bool IsEmpty => _head == null;
 
     /// <summary>
     ///     Adds an item on top of the stack
@@ -33,7 +33,10 @@ public sealed class Stack<TValue>
     /// <param name="value">Value to add</param>
     public void Push(TValue value)
     {
-        // TODO
+        var newNode = new Node<TValue>(value);
+        Count++;
+        newNode.Next = _head; //get to root node
+        _head = newNode; //make the new node the head (the root node)
     }
 
     /// <summary>
@@ -41,12 +44,23 @@ public sealed class Stack<TValue>
     ///     If the stack is empty the default value for the <see cref="TValue" /> type is returned.
     /// </summary>
     /// <returns>Top element of the stack or default</returns>
-    // TODO
+    public TValue? Peek() => _head != null ? _head.Data : default;
 
     /// <summary>
     ///     Gets and removes the top element of the stack.
     ///     If the stack is empty the default value for the <see cref="TValue" /> type is returned.
     /// </summary>
     /// <returns>Top element of the stack or default</returns>
-    // TODO
+    public TValue? Pop()
+    {
+        if (_head == null)
+        {
+            return default;
+        }
+
+        Count--;
+        var data = _head.Data;
+        _head = _head.Next;
+        return data;
+    }
 }

SantaClausInc/Core/Sleigh.cs

@@ -15,13 +15,14 @@ public sealed class Sleigh
     /// <param name="targetCity">City this sleigh will go to during the delivery tour</param>
     public Sleigh(int capacity, string targetCity)
     {
+        TargetCity = targetCity;
         // TODO
     }
 
     /// <summary>
     ///     Gets the target city of this sleigh
     /// </summary>
-    // TODO
+    public string TargetCity { get; }
 
     /// <summary>
     ///     Loads a pile of <see cref="Parcel" /> on the sleigh.