Merge pull request #711 from pooja-git11/patch-2

Create queue_using_linkedlist.cpp

data_structure/queue_using_linkedlist.cpp

@@ -0,0 +1,98 @@
+/*
+    Write a program to implement Queue using linkedlist.
+*/
+#include<iostream>
+
+
+struct linkedlist{
+  int data;
+  linkedlist *next;
+
+};
+class stack_linkedList{
+  public:
+    linkedlist *front;
+    linkedlist *rear;
+    
+    stack_linkedList(){
+        front=rear=NULL;
+    }
+    void enqueue(int);
+    int dequeue();
+    void display();
+
+};
+void stack_linkedList::enqueue(int ele){
+    
+    linkedlist *temp=new linkedlist();
+    temp->data=ele;
+    temp->next=NULL;
+
+    if(front==NULL)
+        front=rear=temp;
+    else{
+        rear->next=temp;
+        rear=temp;
+    }
+}
+int stack_linkedList::dequeue(){
+    linkedlist *temp;
+    int ele;
+    if(front==NULL)
+        std::cout<<"\nStack is empty";
+    else{
+        temp=front;
+        ele=temp->data;
+        if(front==rear)                                         //if length of queue is 1;
+            rear=rear->next;
+        front=front->next;
+        delete(temp);
+    }
+    return ele;
+}
+void stack_linkedList::display(){
+    
+    if(front==NULL)
+        std::cout<<"\nStack is empty";
+    
+    else {
+        
+        linkedlist *temp;
+        temp=front;
+        while(temp!=NULL){
+            std::cout<<temp->data<<" ";
+            temp=temp->next;
+        }
+    }
+}
+
+int main(){
+    
+    int op,data;
+    stack_linkedList ob;
+    std::cout<<"\n1. enqueue(Insertion) ";
+    std::cout<<"\n2. dequeue(Deletion)";
+    std::cout<<"\n3. Display";
+    std::cout<<"\n4. Exit";
+    
+    while(1){
+        std::cout<<"\nEnter your choice ";
+        std::cin>>op;
+        if(op==1)
+        {
+            std::cout<<"Enter data ";
+            std::cin>>data;
+            ob.enqueue(data);
+        }
+        else if(op==2)
+            data=ob.dequeue();
+        else if(op==3)
+            ob.display();
+        else if(op==4)
+            exit(0);
+        else
+            std::cout<<"\nWrong choice ";
+
+    }
+    return 0;
+}