Question

c++

5. You're given the pointer to the head node of a sorted linked list, where the data in the nodes is in ascending order. Delete as few nodes as possible so that the list does not contain any value more than once. The given head pointer may be null indicating that the list is empty. Enter numbers ending with -999 for the linked list: 3 7 11 11 11 24 27 30 42 42 47 55 55 78 89-999 Output: 3 7 11 24 27 30 42 47 55 78 89

Answer 1

// C++ program to create a function to delete the duplicates from the list so that the list does not contain any value more than once

#include <iostream>

using namespace std;

// struct to represent a node in the doubly linked list

struct DNode

{

       int data;

       DNode *next;

       DNode *prev;

};

// function declaration

DNode* insert(DNode *head, int data);

void display(DNode *head);

void destroy(DNode *head);

void deleteDuplicate(DNode *&head);

int main() {

       DNode *head = NULL; // pointer pointing to start of doubly linked list

       int data;

       // input the data(in ascending order) and insert into doubly linked list

       cout<<"Enter numbers ending with -999 for the linked list : "<<endl;

       cin>>data;

       while(data != -999)

       {

             head = insert(head,data);

             cin>>data;

       }

       // display the list

       cout<<"Input List : "<<endl;

       display(head);

       // delete the duplicates from the list so that the list contains value only once

       deleteDuplicate(head);

       // display the modified list

       cout<<"Output List : "<<endl;

       display(head);

       // delete the list

       destroy(head);

       return 0;

}

// function to insert a data into the doubly linked list

DNode* insert(DNode* head, int data)

{

       DNode *node = new DNode;

       node->data = data;

       node->next = NULL;

       node->prev = NULL;

       if(head == NULL)

       {

             head = node;

       }else

       {

             DNode *curr = head;

             while(curr->next != NULL)

                    curr = curr->next;

             curr->next = node;

             node->prev = node;

       }

       return head;

}

// function to display the list

void display(DNode *head)

{

       DNode *curr = head;

       while(curr != NULL)

       {

             cout<<curr->data<<" ";

             curr = curr->next;

       }

       cout<<endl;

}

// function to delete the nodes in the list

void destroy(DNode *head)

{

       while(head != NULL)

       {

             DNode *temp = head;

             head = head->next;

             delete(temp);

       }

}

// function to remove duplicate elements in the list

// Input : head is the pointer pointing to the head node of the sorted linked list, sorted in ascending order

void deleteDuplicate(DNode *&head)

{

       // check if the list is empty or contains only one element, then do nothing

       if(head != NULL && head->next != NULL)

       {

             DNode *currNode = head;

             // loop over the list starting from the first node

             while(currNode != NULL)

             {

                    DNode *nextNode = currNode->next;

                    // loop over the list starting from the list next to currNode

                    // loop that continues till we get the data of nextNode is same as currNode, deleting the nextNode

                    while((nextNode != NULL) && (nextNode->data == currNode->data))

                    {

                           DNode *temp = nextNode;

                           currNode->next = nextNode->next;

                           if(nextNode->next != NULL)

                                 nextNode->next->prev = currNode;

                           nextNode = nextNode->next;

                           delete(temp);

                    }

                    currNode = currNode->next;

             }

       }

}

//end of program

Output:

Enter numbers ending with -999 for the linked list : 3 7 11 11 11 24 27 30 42 42 47 55 55 78 89 -999 Input List : 3 7 11 11 11 24 27 30 42 42 47 55 55 78 89 Output List : 3 7 11 24 27 30 42 47 55 78 89