Dynamic queue (#23)

* Rename Dynamic_Queue.cpp to Dynamic_Queue/Dynamic_Queue.cpp

* Update dq.cpp

* Added dynamic queue

* Update and rename Dynamic_Queue.cpp to User_Friendly_Dynamic_Queue.cpp

* Update and rename Dynamic_Queue/User_Friendly_Dynamic_Queue.cpp to User_Friendly_Dynamic_Queue/User_Friendly_Dynamic_Queue.cpp

User_Friendly_Dynamic_Queue/User_Friendly_Dynamic_Queue.cpp

@@ -0,0 +1,109 @@
+// Dynamic Queue
+#include <iostream>
+
+using namespace std;
+
+struct Node{
+    int info;
+    Node *link;
+};
+
+void Enqueue(int data, Node**, Node**);
+void Dequeue(Node**, Node**);
+void Display(Node*, Node*);
+
+int main()
+{
+    Node *First, *Last;
+    First = NULL;
+    Last = NULL;
+    int data;
+    int ch;
+
+    do
+    {
+        cout << "\n\tMENU";
+        cout << "\n1.Enqueue";
+        cout << "\n2.Dequeue";
+        cout << "\n3.Display";
+        cout << "\n4.Exit";
+        cout << "\nEnter choice...";
+        cin >> ch;
+        switch(ch)
+        {
+        case 1: cout << "\nEnter new data:";
+                cin >> data;
+                Enqueue(data, &First, &Last);
+                break;
+
+        case 2: Dequeue(&First, &Last);
+                break;
+
+        case 3:Display(First, Last);
+                break;
+        }
+    } while(ch >= 1 && ch <= 3);
+
+    return 0;
+}
+
+void Enqueue(int data, Node **F, Node **L)
+{
+    Node *temp = new Node;
+    temp -> info = data;
+
+    if(*L == NULL)
+    {
+        temp -> link = NULL;
+        *F = temp;
+    }
+    else
+        temp -> link = *L;
+
+    (*L) = temp;
+}
+
+void Dequeue(Node **F, Node **L)
+{
+    if(*F == NULL)
+    {
+        cout << "\nUnderflow...";
+        return;
+    }
+    else if(*F == *L)
+    {
+        *F = NULL;
+        *L = NULL;
+        return;
+    }
+
+    Node *temp = NULL;
+    temp = *L;
+
+    while(temp -> link != (*F))
+        temp = temp -> link;
+
+    temp -> link = NULL;
+    *F = temp;
+}
+
+void Display(Node *F, Node *L)
+{
+    Node *temp = NULL;
+
+    if(L == NULL)
+    {
+        cout << "\nUnderflow";
+        return ;
+    }
+
+    temp = L;
+
+    while(temp -> link != NULL)
+    {
+        cout << temp -> info << "->";
+        temp = temp -> link;
+    }
+
+    cout << temp -> info << "->!!!";
+}