Question

Using doubly linked list in c++ with class constructor:

DNode(){
   song = Song();
   prev = NULL;
   next = NULL;
}

DNode(string s, string a, int lenmin, int lensec){
   song = Song(s,a,lenmin,lensec);
   prev = NULL;
   next = NULL;
}

for each node. Write the method:

void moveUp(string t); This method moves a song up one in the playlist. For instance, if you had the following:

Punching in a Dream, The Naked And Famous................3:58

Harder To Breather, Maroon 5................2:52

Where the Rivers Flow, Sons of Maria................3:O3

Still Not a Player, Big Pun Joe................3:56

Train, Brick+Mortar................3:O5

And the song was “Still Not a Player”, the result would be:

Punching in a Dream, The Naked And Famous................3:58

Harder To Breather, Maroon 5................2:52

Still Not a Player, Big Pun Joe................3:56

Where the Rivers Flow, Sons of Maria................3:O3

Train, Brick+Mortar................3:O5

If you move the first song up, it will be moved to the end of the list as follows:

Punching in a Dream, The Naked And Famous................3:58

Harder To Breather, Maroon 5................2:52

Still Not a Player, Big Pun Joe................3:56

Where the Rivers Flow, Sons of Maria................3:O3

Train, Brick+Mortar................3:O5

Moving “Punching in a Dream” up one would result in:

Harder To Breather, Maroon 5................2:52

Still Not a Player, Big Pun Joe................3:56

Where the Rivers Flow, Sons of Maria................3:O3

Train, Brick+Mortar................3:O5

Punching in a Dream, The Naked And Famous................3:58

Answer 1

#include<bits/stdc++.h>
using namespace std;
class Song {
public:
        string songname, album;
        int len_in_min, len_in_sec;

        Song() {}

        Song(string s, string a, int lenmin, int lensec) {
                songname = s;
                album = a;
                len_in_min = lenmin;
                len_in_sec = lensec;
        }

        void printSong() {
                cout << songname << " " << album << " " << len_in_min << ":" << len_in_sec << endl;
        }
};

class DNode {
public:
        Song song;
        DNode* next;
        DNode* prev;

        DNode() {
                song = Song();
                prev = NULL;
                next = NULL;
        }
        DNode(string s, string a, int lenmin, int lensec) {
                song = Song(s, a, lenmin, lensec);
                prev = NULL;
                next = NULL;
        }
};


class DLinkedList {
public:
        DNode* head = NULL;
        DNode* tail = NULL;

        void add(string s, string a, int lenmin, int lensec) {
                if (head == NULL) {
                        head = new DNode(s, a, lenmin, lensec);
                        // (head->song).printSong();
                        tail = head;
                } else {
                        tail->next = new DNode(s, a, lenmin, lensec);
                        tail->next->prev = tail;
                        tail = tail->next;
                }
        }

        void MoveUp(string s) {
                DNode* curr = head;

                while ((curr->song).songname != s && curr != NULL) {
                        curr = curr->next;
                }

                DNode* a = curr->prev->prev;
                DNode* b = curr->prev;
                DNode* c = curr;
                DNode* d = curr->next;

                a->next = c;
                c->prev = a;
                c->next = b;
                b->prev = c;
                b->next = d;
                d->prev = b;

        }
        void printList() {
                DNode* curr = head;

                while (curr != NULL) {
                        (curr->song).printSong();
                        curr = curr->next;
                }
        }
};

int main() {

        DLinkedList D;

        D.add("Punching in a Dream", "The Naked And Famous", 3, 58);
        D.add("Harder To Breather", "Maroon 5", 2, 52);
        D.add("Where the Rivers Flow", " Sons of Maria", 3, 3);
        D.add("Still Not a Player", "Big Pun Joe", 3, 56);
        D.add("Train", " Brick+Mortar", 3, 5);

        D.printList();

        D.MoveUp("Still Not a Player");

        cout << "\nSelected Song: Still Not a Player\n" << endl;

        D.printList();

        return 0;
}

OUTPUT: