DoublyLL.cpp

#include <iostream>
#include <cstdlib>
using namespace std;

struct ListNode
{
    int data;
    ListNode* prev;
    ListNode* next;
}* list = NULL;

void insert(int value){
    ListNode* newNode = (ListNode*)malloc(sizeof(ListNode));
    newNode->data = value;
    newNode->next = NULL;
    if (list == NULL)
    {
        list = newNode;
        list->prev = NULL;
        return;
    }
    else{
        ListNode* current = list;
        while (current->next != NULL)
        {
            current = current->next;
        }
        current->next = newNode;
        newNode->prev = current;
    }
    
}
bool search(int value){
    if (list == NULL)
    {
        cout<<"List is empty"<<endl;
    }
    else{
        ListNode* current = list;
        while (current != NULL)
        {
            if (current->data == value)
            {
                return true;
            }
            current = current->next;
        }
    }
    return false;
}
void displayForward(){
    if (list == NULL)
    {
        cout<<"List is empty"<<endl;
    }
    else{
        ListNode* current = list;
        while (current != NULL)
        {
            cout<<current->data<<" ";
            current = current->next;
        }
        cout<<endl;
    }
}
void displayPrev(){
    if (list == NULL)
    {
        cout<<"List is empty"<<endl;
    }
    else{
        ListNode* current = list;
        while (current->next != NULL)
        {
            current = current->next;
        }
        while (current != NULL)
        {
            cout<<current->data<<" ";
            current = current->prev;
        }
        cout<<endl;
    }
}
void Delete(int toDel){
    if (list == NULL)
    {
        cout<<"List is empty"<<endl;
        return;
    }
    ListNode* current = list;
    ListNode* temp;
    while (current != NULL)
    {
        if (toDel == current->data)
        {
            if (current == list)
            {
                list = current->next;
                if (list != NULL) {
                    list->prev = NULL;
                }
                free(current);
                current = list;
            }
            else if (current->next == NULL)
            {
                current->prev->next = NULL;
                free(current);
                current = NULL;
            }
            else{
                temp = current;
                current->prev->next = current->next;
                current->next->prev = current->prev;
                current = current->next;
                free(temp);
            }
        }
        else{
            current = current->next;
        }
    }
}
int main(int argc, char const *argv[])
{
    int option;
    int value;
    while (true)
    {
        cout<<"1: Insert"<<endl;
        cout<<"2: Search"<<endl;
        cout<<"3: Delete"<<endl;
        cout<<"4: DisplayForward"<<endl;
        cout<<"5: DisplayReverse"<<endl;

        cout<<"Enter your choice ";
        cin>> option;
        switch (option)
        {
        case 1:
            cout<<"Enter value to insert ";
            cin>> value;
            insert(value);
            break;
        case 2:
            cout<<"Enter value to search ";
            cin>> value;
            if (search(value))
            {
                cout<<"Value Found"<<endl;
            }
            else{
                cout<<"Value Not Found"<<endl;
            }
            break;
        case 3:
            cout<<"Enter value to delete ";
            cin>>value;
            Delete(value);
            break;
        case 4:
            displayForward();
            break;
        case 5:
            displayPrev();
            break;
        default:
            cout<<"Exit Successfully"<<endl;
            break;
        }
        if (option > 5)
        {
            break;
        }
    }

    return 0;
}