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circularLists.cpp
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circularLists.cpp
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#include <iostream>
using namespace std;
struct node {
int data;
node *next;
};
void insert(node **head,int data,bool beg) {
node *newNode = new node;
if(!newNode) {
cout<<"Memory allocation error"<<endl;
return;
}
newNode->data = data;
newNode->next = newNode;
if(*head == NULL) {
*head = newNode;
return;
}
node *current = *head;
while(current->next != *head)
current = current->next;
newNode->next = *head;
current->next = newNode;
if(beg)
*head = newNode;
}
void delAtEnd(node **head) {
if(*head == NULL) {
cout<<"List empty"<<endl;
return;
}
int isOnlyOneNode = 0;
node *current = *head, *temp = NULL;
while(current->next != *head) {
temp = current;
current = current->next;
}
if(temp == NULL) {
delete current;
*head = NULL;
}
else {
temp->next = current->next;
delete current;
}
}
void delAtBeg(node **head) {
if(*head == NULL) {
cout<<"List empty"<<endl;
return;
}
int isOnlyOneNode = 0;
node *current = *head;
if(current->next == *head)
isOnlyOneNode = 1;
while(current->next != *head)
current = current->next;
node *temp = *head;
current->next = temp->next;
if(isOnlyOneNode)
*head = NULL;
else
*head = current->next;
delete temp;
}
void traversal(node **head) {
if(*head == NULL) {
cout<<"List empty"<<endl;
return;
}
node *current = *head;
do {
cout<<current->data<<" ";
current = current->next;
}while(current != *head);
cout<<endl;
}
void delList(node **head) {
if(*head == NULL)
return;
node *current = *head;
while(current->next != *head) {
node *temp = current->next;
current->next = temp->next;
delete temp;
}
delete current;
}
int main() {
int ch,data;
node *head = NULL;
while(1) {
cout<<"1. InsertAtBeg 2. InsertAtEnd 3. DeleteAtBeg 4. DeleteAtEnd 5. Traversal 6. Exit\n";
cin>>ch;
switch(ch) {
case 1: cout<<"Enter data"<<endl;
cin>>data;
insert(&head,data,true);
break;
case 2: cout<<"Enter data\n";
cin>>data;
insert(&head,data,false);
break;
case 3: delAtBeg(&head);
break;
case 4: delAtEnd(&head);
break;
case 5: traversal(&head);
break;
}
if(ch == 6)
break;
}
delList(&head);
return 0;
}