Merge branch 'main' of github.com:princomp/princomp.github.io

Author: aubertc

source/code/projects/CList_ICollection/CList_ICollection/CList.cs

@@ -181,4 +181,32 @@ IEnumerator IEnumerable.GetEnumerator()
   }
 
   /* We are done realizing the ICollection class. */
+
+  // One last method, to remove the last cell and
+  // returns its value.
+  public T RemoveL()
+  {
+    if (isReadonly)
+    {
+      throw new InvalidOperationException(
+        "List is read-only"
+      );
+    }
+    if (IsEmpty())
+    {
+      throw new InvalidOperationException(
+        "Cannot remove last cell from an empty list!."
+      );
+    }
+    T data;
+
+    Cell cCell = first;
+    while (cCell.Next != null && cCell.Next.Next != null)
+    {
+      cCell = cCell.Next;
+    }
+    data = cCell.Next.Data;
+    cCell.Next = null;
+    return data;
+  }
 }

source/code/projects/CList_ICollection/CList_ICollection/Program.cs

@@ -91,5 +91,31 @@ static void Main(string[] args)
     {
       Console.Write(i + " ");
     }
+    // Last, we test the RemoveL method
+    myList1.IsReadOnly = false;
+    Console.WriteLine("\nThe list contains:");
+    foreach (int i in myList1)
+    {
+      Console.Write(i + " ");
+    }
+    for (int i = 0; i < myList1.Count; i++)
+    {
+      try
+      {
+        Console.WriteLine(
+          "\nValue removed: " + myList1.RemoveL()
+        );
+      }
+      catch (Exception e)
+      {
+        Console.WriteLine(e.Message);
+      }
+    }
+
+    Console.WriteLine("\nThe list contains:");
+    foreach (int i in myList1)
+    {
+      Console.Write(i + " ");
+    }
   }
 }

source/code/projects/RBTree/RBTree/Program.cs

@@ -0,0 +1,13 @@
+using System;
+
+class Program
+{
+    static void Main()
+    {
+        RBTree<int> btree = new RBTree<int>();
+        btree.Insert(1);
+        btree.Insert(2);
+        btree.Insert(3);
+        btree.Insert(4);
+    }
+}

source/code/projects/RBTree/RBTree/RBTree.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Collections.Generic;
+
+public class RBTree<T>
+{
+  private class Node
+  {
+    public T Data { get; set; }
+    public Node left;
+    public Node right;
+
+    public Node(
+      T dataP = default(T),
+      Node leftP = null,
+      Node rightP = null
+    )
+    {
+      Data = dataP;
+      left = leftP;
+      right = rightP;
+    }
+}
+  private Node root;
+
+  public RBTree()
+  {
+    root = null;
+  }
+    public void Insert(T dataP)
+    {
+        root = Insert(dataP, root);
+    }
+
+    private Node Insert(T dataP, Node nodeP)
+    {
+        if (nodeP == null)
+        {
+            return new Node(dataP, null, null);
+        }
+        else
+        {
+            Random gen = new Random();
+            if(gen.NextDouble() > 0.5)
+            {
+                nodeP.left = Insert(dataP, nodeP.left);
+            }
+            else
+            {
+                nodeP.right = Insert(dataP, nodeP.right);
+            }
+        }
+        return nodeP;
+    }
+}

source/code/projects/Tree/Tree/BSTree.cs

@@ -33,19 +33,19 @@ private Node Insert(T dataP, Node nodeP)
     return nodeP;
   }
 
-    // Finding into a BSTree
+  // Finding into a BSTree
 
-    public override bool Find(T dataP)
+  public override bool Find(T dataP)
+  {
+    bool found = false;
+    if (root != null)
     {
-        bool found = false;
-        if (root != null)
-        {
-            found = Find(dataP, root);
-        }
-        return found;
+      found = Find(dataP, root);
     }
+    return found;
+  }
 
-    private bool Find(T dataP, Node nodeP)
+  private bool Find(T dataP, Node nodeP)
   {
     bool found = false;
     if (nodeP != null)

source/code/projects/Tree/Tree/BTree.cs

@@ -21,8 +21,9 @@ public Node(
       left = leftP;
       right = rightP;
     }
-        // Displaying a Node is only 
-        // displaying its data.
+
+    // Displaying a Node is only
+    // displaying its data.
     public override string ToString()
     {
       return Data.ToString();
@@ -108,7 +109,7 @@ public virtual bool Find(T dataP)
     bool found = false;
     if (root != null)
     {
-      found = Find(root, dataP);
+      found = Find(dataP, root);
     }
     return found;
   }

source/code/projects/Tree/Tree/Program.cs

@@ -7,40 +7,40 @@ static void Main()
     BSTree<int> btree = new BSTree<int>();
     Console.WriteLine(btree);
 
-        /*
- * The purpose of this example is to illustrate that
- * the order in which values are inserted matter.
- */
-        btree.Clear();
-        btree.Insert(10);
-        btree.Insert(6);
-        btree.Insert(13);
-        btree.Insert(12);
-        btree.Insert(14);
-        Console.WriteLine(btree);
-        btree.Clear();
-        btree.Insert(14);
-        btree.Insert(12);
-        btree.Insert(13);
-        btree.Insert(6);
-        btree.Insert(10);
-        Console.WriteLine(btree);
+    /*
+* The purpose of this example is to illustrate that
+* the order in which values are inserted matter.
+*/
+    btree.Clear();
+    btree.Insert(10);
+    btree.Insert(6);
+    btree.Insert(13);
+    btree.Insert(12);
+    btree.Insert(14);
+    Console.WriteLine(btree);
+    btree.Clear();
+    btree.Insert(14);
+    btree.Insert(12);
+    btree.Insert(13);
+    btree.Insert(6);
+    btree.Insert(10);
+    Console.WriteLine(btree);
 
-        /* Second example, we begin by clearing the tree. */
+    /* Second example, we begin by clearing the tree. */
 
-        btree.Clear();
-        btree.Insert(10);
-        // Attempting to insert the same value 
-        // twice raises an exception:
-        try
-        {
-            btree.Insert(10);
-        }
-        catch(Exception e)
-        {
-            Console.WriteLine(e.Message);
-        }
-        btree.Insert(11);
+    btree.Clear();
+    btree.Insert(10);
+    // Attempting to insert the same value
+    // twice raises an exception:
+    try
+    {
+      btree.Insert(10);
+    }
+    catch (Exception e)
+    {
+      Console.WriteLine(e.Message);
+    }
+    btree.Insert(11);
     btree.Insert(30);
     btree.Insert(7);
     Console.WriteLine(btree);
@@ -80,7 +80,5 @@ static void Main()
     {
       Console.WriteLine(i + " occurs: " + btree.Find(i));
     }
-
-
   }
 }

source/diag/gra/bstree_example_5.txt

@@ -0,0 +1,6 @@
+%%% The "random" binary tree obtained by inserting 1, 2, 3 and 4 (in that order).
+
+A((1))-->B((2))
+A-->C((3))
+C~~~H1:::hidden
+C-->D((4))

source/order

@@ -96,6 +96,9 @@
 ./exercises/data/1darrays.md
 ./exercises/data/2darrays.md
 ./exercises/data/lists.md
+./exercises/data/stacks.md
+./exercises/data/queues.md
+./exercises/data/trees.md
 ./exercises/control/
 ./exercises/control/conditionals.md
 ./exercises/control/iteratives.md

source/solutions/data/lists.md

@@ -26,6 +26,12 @@ tags:
     - This restriction applies to queues or stacks (depending how "beginning" is interpreted), but not to lists.   
     </details>
 
+#. Implementing a list as a doubly linked list (as opposed to singly linked list) allows to …
+    
+    - [ ] use fewer attributes.
+    - [x] keep track of the end of the list.
+    - [ ] store more elements.
+    - [ ] insert at the beginning of the list faster.
 
 ## Exercises
 
@@ -41,7 +47,8 @@ tags:
         }
         public CList(){first = null;}
     }
-    ``` 
+    ```   
+
     Write…
        
     #. … a `IsEmpty` property that is `true` if the `CList` calling object is empty.
@@ -57,7 +64,7 @@ tags:
         }
         ```
         </details>
-    #. … the `AddF` method that add a cell at the beginning of the CList (to the left).
+    #. … a `AddF` method that takes an argument of type `T` and adds it at the beginning ("to the left") of the `CList` calling object.
 
         <details>
         <summary>Solution</summary>
@@ -70,6 +77,36 @@ tags:
         }
         ```
         </details>
+    #. … a `RemoveL` method that remove the value at the end ("to the right") of the `CList` calling object and returns it.
+    
+        <details>
+        <summary>Solution</summary>        
+        ```
+        public T RemoveL()
+            {
+                if (first == null)
+                {
+                    throw new InvalidOperationException(
+                                "Cannot remove last cell from an empty list!."
+                                );
+                }
+                T data;
+
+                Cell cCell = first;
+                while (
+                    cCell.Next != null && cCell.Next.Next != null
+                )
+                {
+                    cCell = cCell.Next;
+                }
+                data = cCell.Next.Data;
+                cCell.Next = null;
+                return data;
+            }
+        ```
+        </details>
+        
+
     #. … a series of statements, to be inserted in a `Main` method, that a. create a `CList` object capable of containing `char`, b. insert the elements `'b'` and `'/'` in it, c. displays whether it is empty using `IsEmpty`.
 
         <details>
@@ -84,7 +121,14 @@ tags:
         Console.WriteLine("myList1 is empty:" + myList1.IsEmpty);
         ```
         </details>
-    
+        
+    #. If the `AddF` and `RemoveL` were the only two methods to add to and to remove from the list, what would be the name of the data-structure we actually just implemented?
+
+        <details>
+        <summary>Solution</summary>
+        It would be a queue.
+        </details>
+        
 #. Briefly explain the purpose of the `IsReadonly` property from the `ICollection<T>` interface, and list at least two methods in a List implementation realizing `ICollection<T>` that should use it.
 
     <details>