Merge pull request #749 from ask2sm/patch-19

queue.cpp

Author: probot-auto-merge[bot]

Queue/queue.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+using namespace std;
+struct node {
+   int data;
+   struct node *next;
+};
+struct node* front = NULL;
+struct node* rear = NULL;
+struct node* temp;
+void Insert() {
+   int val;
+   cout<<"Insert the element in queue : "<<endl;
+   cin>>val;
+   if (rear == NULL) {
+     // rear =(struct node *)new(sizeof(struct node));
+     rear=new(struct node);
+      rear->next = NULL;
+      rear->data = val;
+      front = rear;
+   } else {
+      //temp=(struct node *)new(sizeof(struct node));
+      temp=new(struct node);
+      rear->next = temp;
+      temp->data = val;
+      temp->next = NULL;
+      rear = temp;
+   }
+}
+void Delete() {
+   temp = front;
+   if (front == NULL) {
+      cout<<"Underflow"<<endl;
+      return;
+   }
+   else
+   if (temp->next != NULL) {
+      temp = temp->next;
+      cout<<"Element deleted from queue is : "<<front->data<<endl;
+      delete(front);
+      front = temp;
+   } else {
+      cout<<"Element deleted from queue is : "<<front->data<<endl;
+      delete(front);
+      front = NULL;
+      rear = NULL;
+   }
+}
+void Display() {
+   temp = front;
+   if ((front == NULL) && (rear == NULL)) {
+      cout<<"Queue is empty"<<endl;
+      return;
+   }
+   cout<<"Queue elements are: ";
+   while (temp != NULL) {
+      cout<<temp->data<<" ";
+      temp = temp->next;
+   }
+   cout<<endl;
+}
+int main() {
+   int ch;
+   cout<<"1) Insert element to queue"<<endl;
+   cout<<"2) Delete element from queue"<<endl;
+   cout<<"3) Display all the elements of queue"<<endl;
+   cout<<"4) Exit"<<endl;
+do {
+   cout<<"Enter your choice : "<<endl;
+   cin>>ch;
+   switch (ch) {
+      case 1: Insert();
+         break;
+      case 2: Delete();
+         break;
+      case 3: Display();
+         break;
+      case 4: cout<<"Exit"<<endl;
+         break;
+      default: cout<<"Invalid choice"<<endl;
+   }
+} while(ch!=4);
+   return 0;
+}