add deletion in cll

Author: muskanlalit18

C++/Data-Structures/LinkedList/DeletionCircularLL.cpp

@@ -0,0 +1,225 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+
+//Test cases:
+//1
+//5
+//1 2 3 4 5
+//Expected Output:
+//2 3 4 5
+//input (index = 3)
+//2 3 4
+//2 3
+
+
+//Class for creation of a Node
+class Node{
+ public:
+ int data;
+ Node* next;
+ Node(int data)
+ {
+ this->data = data;
+ this->next = NULL;
+ }
+};
+
+//Class for implementation of CLL
+class CLL{
+ public:
+ //to keep track of head of the LL
+ Node* head;
+ //to keep track of the last node of LL.
+ Node* tail;
+ CLL()
+ {
+ this -> head = NULL;
+ this -> tail = NULL;
+ }
+ //Since this code is to demonstrate deletion, we will only use InsertAtEnd in the CLL
+ void insertAtEnd(int data)
+ {
+
+ //Create new node
+ Node* newNode = new Node(data);
+
+ //If list is empty
+ if(head == NULL)
+ {
+ head = newNode;
+ tail = newNode;
+ tail -> next = head;
+ }
+
+ //If there are elements already present in the list
+ else
+ {
+ tail -> next = newNode;
+ tail = newNode;
+ tail -> next = head;
+ }
+ }
+
+
+ //Delete node from the beginning
+ void deleteFromBeg()
+ {
+ Node* temp = head;
+ if(temp == NULL)
+ {
+ cout<<"LL is empty!"<<endl;
+ return;
+ }
+ else if(temp->next == temp)
+ {
+ head = NULL;
+ tail = NULL;
+ free(temp);
+ return;
+ }
+ head = head -> next;
+ tail -> next = head;
+ free(temp);
+ }
+
+ //Delete Node from middle given the index
+ void deleteFromMid(int index)
+ {
+ if(index == 0)
+ {
+ deleteFromBeg();
+ return;
+ }
+ Node* temp = head;
+ if(temp == NULL)
+ {
+ cout<<"LL is empty!"<<endl;
+ return;
+ }
+ if(temp -> next == temp)
+ {
+ head = NULL;
+ tail = NULL;
+ free(temp);
+ return;
+ }
+ int count = 0;
+
+ //Traverse to the node to be deleted
+ while(count != index - 1 && temp->next != tail)
+ {
+ temp = temp -> next;
+ count++;
+ }
+
+ //If node to be deleted is the next node
+ if(count == index - 1)
+ {
+ Node* temp1 = temp->next;
+ temp->next = temp1->next;
+ if(temp1 == tail)
+ {
+ tail = temp;
+ }
+ free(temp1);
+ }
+
+ //If last node has been reached but index has not been found
+ if(temp->next == tail && count!=index-1)
+ {
+ cout<<"Index out of bounds!"<<endl;
+ return;
+ }
+
+ }
+
+ //Delete last node
+ void deleteFromEnd()
+ {
+ Node* temp = head;
+
+ //If LL is empty
+ if(temp == NULL)
+ {
+ cout<<"LL is empty"<<endl;
+ return;
+ }
+
+ //If LL has just one element
+ else if(temp -> next == temp)
+ {
+ head = NULL;
+ tail = NULL;
+ free(temp);
+ return;
+ }
+
+ //Otherwise
+ while(temp -> next != tail)
+ {
+ temp = temp -> next;
+ }
+ Node* temp1 = temp->next;
+ temp -> next = temp1 -> next;
+ tail = temp;
+ free(temp1);
+
+ }
+ //To display the CLL
+ void display()
+ {
+ Node* temp = head;
+ if(temp == NULL)
+ {
+ cout<<"Empty LL!"<<endl;
+ return;
+ }
+ cout<<temp->data<<" ";
+ temp = temp->next;
+ while(temp != head)
+ {
+ cout<<temp->data<<" ";
+ temp = temp->next;
+ }
+ cout<<endl;
+ }
+
+ };
+ int main()
+ {
+ int test_cases;
+ cout<<"Enter number of test cases:"<<endl;
+ cin>>test_cases;
+ while(test_cases--)
+ {
+ cout<<"Enter number of elements:"<<endl;
+ int n;
+ cin>>n;
+ int index;
+ CLL* linkedList = new CLL();
+ cout<<"Enter elements: "<<endl;
+ while(n--)
+ {
+ int data;
+ cin>>data;
+
+ linkedList->insertAtEnd(data);
+ }
+ cout<<"Current LL is:"<<endl;
+ linkedList -> display();
+ cout<<"Deleting first node:"<<endl;
+ linkedList -> deleteFromBeg();
+ linkedList -> display();
+ cout<<"Enter index to delete element from (0-based indexing):"<<endl;
+ cin>>index;
+ cout<<"Deleting node at index "<<index<<":"<<endl;
+ linkedList -> deleteFromMid(index);
+ linkedList -> display();
+ cout<<"Deleting last node:"<<endl;
+ linkedList -> deleteFromEnd();
+ linkedList -> display();
+ }
+
+ return 0;
+ }