Data-Structure-Algorithm/Queue_LinkedList.cpp at main · Ritika032/Data-Structure-Algorithm · GitHub

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#include<iostream>
#include<malloc.h>
usingnamespacestd;
structnode {
int data;
structnode *next;
};
structnode *front = NULL, *rear = NULL;
structnode* temp;
voidInsert() {
int val;
 cout<<"Insert the element in queue : "<<endl;
 cin>>val;
if (rear == NULL)
 {
 rear = (structnode *)malloc(sizeof(structnode));
 rear->next = NULL;
 rear->data = val;
 front = rear;
 }
else
 {
 temp=(structnode *)malloc(sizeof(structnode));
 rear->next = temp;
 temp->data = val;
 temp->next = NULL;
 rear = temp;
 }
}
voidDelete()
{
 temp = front;
if (front == NULL)
 {
 cout<<"Underflow";
 }
elseif(temp->next != NULL)
 {
 temp = temp->next;
 cout<<"Element deleted from queue is : "<<front->data<<endl;
free(front);
 front = temp;
 }
else
 {
 cout<<"Element deleted from queue is : "<<front->data<<endl;
free(front);
 front = NULL;
 rear = NULL;
 }
}
voidDisplay() {
 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;
}
intmain() {
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 : ";
 cin>>ch;
switch (ch) {
case1: Insert();
break;
case2: Delete();
break;
case3: Display();
break;
case4: cout<<"Exit"<<endl;
break;
default: cout<<"Invalid choice"<<endl;
 }
 } while(ch!=4);
return0;
}