#include <iostream>
#include <fstream>

using namespace std;

struct Node {
    int data;
    Node *next;
    Node *prev;
};

typedef struct DLinkedList *List;
struct DLinkedList {
    Node *first;
};

void AppendEnd( int v );
bool Search( int value );
void Delete( int value );
List list;

// test
int main()
{
    AppendEnd(4);
    AppendEnd(6);
    if(Search(4)) cout << "true";
    else cout << "false";
    if(Search(6)) cout << "\ttrue\n";
    Delete(6);
    if(Search(6)) cout << "true";
    return 0;
}



// Gan gia tri value vao cuoi cua linked-list
void AppendEnd( int value ) {

    Node *node = new Node;
    node->data = value;
    node->next = NULL;
    node->prev = NULL;

    if( list == NULL ) {
        list = new DLinkedList;
        list->first = node;
    }
    else {
        Node *curr = list->first;
        while( curr->next != NULL )
            curr = curr->next;

        curr->next = node;
        node->prev = curr;
    }
}


// tim xem trong linked list co gia tri value hay ko
bool Search( int value ) {

    Node *curr = list->first;

    while( curr != NULL ) {
        if( curr->data == value )
            return true;
        curr = curr->next;
    }
    return false;
}


// Xoa element dau tien co gia tri value trong list
void Delete( int value ) {

    Node *curr = list->first;
    while( curr != NULL ) {
        if( curr->data == value ) {
            curr->next->prev = curr->prev;
            curr->prev->next = curr->next;
            delete curr;
            return;
        }
        curr = curr->next;
    }
}