DLLIST

  struct node
{
    int val;
     node *next;
     node *prev;
};


struct DLList
    {
        node *head ,*tail;
        DLList();

        void insert (int x);
        void addToHead(int x);
        void addToTail (int x);
        void delTail();
        void delHead();
        void Maximum();
        void Minimum();
        void del(int t);
        void print();
    };


#include <iostream>
using namespace std;

DLList::DLList(){
    head=tail=NULL;
}

void DLList::insert (int x){
    node *n=new node();
    n->val=x;
    if(head == NULL){
        head=tail=n;
        head->prev=NULL;
        tail->next=NULL;
        return;
    }
          tail->next=n;
    n->prev=tail;
    tail=n;
    tail->next=NULL;
}
void DLList::del(int x){
    node *cur =head;
    if(cur==NULL)return;
    while(cur!=NULL){
        if(cur->val==x)break;
        cur=cur->next;
    }
    if(cur==NULL)return;
    if(cur==head && cur ==tail){
        head=tail=NULL;
        delete cur;
        return;
    }
    if(cur==head){
        head=head->next;
        delete cur;
        head->prev=NULL;
        return;
    }
    if(cur==tail){
        tail=tail->prev;
        delete cur;
        tail->next=NULL;
        return;
    }
    cur->next->prev=cur->prev;
    cur->prev->next=cur->next;
    delete cur;
}

void DLList::print(){
    node *cur=head;
    while(cur!=NULL){
        cout<<cur->val<<" ";
        cur=cur->next;
    }
    cout<<endl;
}
void DLList::addToHead(int x){
    node *n=new node();
    n->val=x;
    if(head==NULL){
        head=tail=n;
        n->prev=NULL;
        n->next=NULL;
        return;
    }
    n->next=head;
    head=n;
    n->prev=NULL;
}

void DLList::addToTail (int x){
    node *n=new node();
    n->val=x;
    if(head == NULL){
        head=tail=n;
        head->prev=NULL;
        tail->next=NULL;
        return;
    }
    tail->next=n;
    n->prev=tail;
    tail=n;
    tail->next=NULL;
}

void DLList::delHead(){
    node *cur =head;
    if(cur==NULL)
        return;
    if(head ==tail){
        head=tail=NULL;
        delete cur;
        return;
    }
    head=head->next;
    head->prev=NULL;
    delete cur;
    return;
}

void DLList:: delTail(){
    node *t=tail;
    if(head==NULL)
        return;
    if(head==tail){
        head=tail=NULL;
        delete t;
        return;
    }
    tail=tail->prev;
    tail->next=NULL;
    delete t;
    return;
}

void DLList::Maximum(){
    node *n=head;
    if(head==NULL)
        return;
    int max=head->val;
    while(n!=NULL){
        if(n->val > max)
            max=n->val;
        n=n->next;
    }
    cout<<"Maximum : "<<max<<endl;
    if(head==tail)
        return;
    int max2=head->val;
    n=head;
    while(n!=NULL){
        if(n->val>max2 && n->val<max)
            max2=n->val;
        n=n->next;
    }
        cout<<"Second Maximum : "<<max2<<endl;
}

void DLList::Minimum(){
    node *n=head;
    if(head==NULL)
        return;
    int min=head->val;
    while(n!=NULL){
        if(n->val < min)
            min=n->val;
        n=n->next;
    }
    cout<<"Minimum : "<<min<<endl;
    if(head==tail)
        return;
    int min2=head->val;
    n=head;
    while(n!=NULL){
        if(n->val < min2 && n->val > min)
            min2=n->val;

        n=n->next;
    }
        cout<<"Second Minimum : "<<min2<<endl;
}

int main(){
    DLList k;/*k=new DLList();*/
    k.insert(5);
    k.insert(7);
    /*
    k->insert(11);
    k->insert(-6);
    k->print();
    k->del(2);
    k->print();
    k->del(11);
    k->print();
    k->addToHead(12);
    */
    k.print();
    /*
    k->addToTail(-7);
    k->print();
    k->delHead();
    k->print();
    k->delTail();
    k->print();
    k->Maximum();
    k->Minimum();*/
    return 0;
}