C++ Program to Implement LeftList Heap

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C++ Program to Implement LeftList Heap

C++ Program to Implement LeftList Heap

#include <iostream>

    #include <cstdlib>

    using namespace std;

    /* Node Class Declaration     */

    class LeftistNode

    {

        public:

            int element;

            LeftistNode *left;

            LeftistNode *right;

            int npl;

            LeftistNode(int & element, LeftistNode *lt = NULL,

                        LeftistNode *rt = NULL, int np = 0)

            {

                this->element = element;

                right = rt;

                left = lt,

                npl =  np;

            }

    };

    /* Class Declaration     */

    class LeftistHeap

    {

        public:

            LeftistHeap();

            LeftistHeap(LeftistHeap &rhs);

            ~LeftistHeap();

            bool isEmpty();

            bool isFull();

            int &findMin();

            void Insert(int &x);

            void deleteMin();

            void deleteMin(int &minItem);

            void makeEmpty();

            void Merge(LeftistHeap &rhs);

            LeftistHeap & operator=(LeftistHeap &rhs);

        private:

            LeftistNode *root;

            LeftistNode *Merge(LeftistNode *h1, LeftistNode *h2);

            LeftistNode *Merge1(LeftistNode *h1, LeftistNode *h2);

            void swapChildren(LeftistNode * t);

            void reclaimMemory(LeftistNode * t);

            LeftistNode *clone(LeftistNode *t);

    };

    /* Construct the leftist heap.     */

    LeftistHeap::LeftistHeap()

    {

        root = NULL;

    }

    /* Copy constructor.     */

    LeftistHeap::LeftistHeap(LeftistHeap &rhs)

    {

        root = NULL;

        *this = rhs;

    }

    /* Destruct the leftist heap.     */

    LeftistHeap::~LeftistHeap()

    {

        makeEmpty( );

    }

    /* Merge rhs into the priority queue.

     * rhs becomes empty. rhs must be different from this.   */

    void LeftistHeap::Merge(LeftistHeap &rhs)

    {

        if (this == &rhs)

            return;

        root = Merge(root, rhs.root);

        rhs.root = NULL;

    }

    /* Internal method to merge two roots. Deals with deviant cases and calls recursive Merge1.     */

    LeftistNode *LeftistHeap::Merge(LeftistNode * h1, LeftistNode * h2)

    {

        if (h1 == NULL)

            return h2;

        if (h2 == NULL)

            return h1;

        if (h1->element < h2->element)

            return Merge1(h1, h2);

        else

            return Merge1(h2, h1);

    }

    /* Internal method to merge two roots. Assumes trees are not empty, and h1's root contains smallest item.     */

    LeftistNode *LeftistHeap::Merge1(LeftistNode * h1, LeftistNode * h2)

    {

        if (h1->left == NULL)

            h1->left = h2;

        else

        {

            h1->right = Merge(h1->right, h2);

            if (h1->left->npl < h1->right->npl)

                swapChildren(h1);

            h1->npl = h1->right->npl + 1;

        }

        return h1;

    }

    /* Swaps t's two children.     */

    void LeftistHeap::swapChildren(LeftistNode * t)

    {

        LeftistNode *tmp = t->left;

        t->left = t->right;

        t->right = tmp;

    }

    /* Insert item x into the priority queue, maintaining heap order.     */

    void LeftistHeap::Insert(int &x)

    {

        root = Merge(new LeftistNode(x), root);

    }

    /* Find the smallest item in the priority queue. Return the smallest item, or throw Underflow if empty.     */

    int &LeftistHeap::findMin()

    {

        return root->element;

    }

    /* Remove the smallest item from the priority queue. Throws Underflow if empty.     */

    void LeftistHeap::deleteMin()

    {

        LeftistNode *oldRoot = root;

        root = Merge(root->left, root->right);

        delete oldRoot;

    }

    /* Remove the smallest item from the priority queue. Pass back the smallest item, or throw Underflow if empty.     */

    void LeftistHeap::deleteMin(int &minItem)

    {

        if (isEmpty())

        {

            cout<<"Heap is Empty"<<endl;

            return;

        }

        minItem = findMin();

        deleteMin();

    }

    /* Test if the priority queue is logically empty. Returns true if empty, false otherwise.     */

    bool LeftistHeap::isEmpty()

    {

        return root == NULL;

    }

    /* Test if the priority queue is logically full. Returns false in this implementation.     */

    bool LeftistHeap::isFull()

    {

        return false;

    }

    /* Make the priority queue logically empty.     */

    void LeftistHeap::makeEmpty()

    {

        reclaimMemory(root);

        root = NULL;

    }

    /* Deep copy.     */

    LeftistHeap &LeftistHeap::operator=(LeftistHeap & rhs)

    {

        if (this != &rhs)

        {

            makeEmpty();

            root = clone(rhs.root);

        }

        return *this;

    }

    /* Internal method to make the tree empty.      */

    void LeftistHeap::reclaimMemory(LeftistNode * t)

    {

        if (t != NULL)

        {

            reclaimMemory(t->left);

            reclaimMemory(t->right);

            delete t;

        }

    }

    /* Internal method to clone subtree.      */

    LeftistNode *LeftistHeap::clone(LeftistNode * t)

    {

        if (t == NULL)

            return NULL;

        else

            return new LeftistNode(t->element, clone(t->left), clone(t->right), t->npl);

    }

    int main()

    {

        LeftistHeap h;

        LeftistHeap h1;

        LeftistHeap h2;

        for (int i = 0; i < 20; i++)

        {

            if (i % 2 == 0)

            {

                h.Insert(i);

                cout<<"Element"<<i<<" inserted in Heap 1"<<endl;

            }

            else

            {

                h1.Insert(i);

                cout<<"Element"<<i<<" inserted in Heap 2"<<endl;

            }

        }

        h.Merge(h1);

        h2 = h;

        for (int i = 0; i < 20; i++)

        {

            int x;

            h2.deleteMin(x);

            cout<<"Element "<<x<<" Deleted"<<endl;

            if (h2.isEmpty())

            {

                cout<<"The Heap is Empty"<<endl;

                break;

            }

        }

        return 0;

    }

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Final Words

C++ Program to Implement LeftList Heap We hope all your doubts about this topic will be resolved. See you again in the next article Thank you.

Hi, I'm Ranjith a full-time Blogger, YouTuber, Affiliate Marketer, & founder of Coding Deekshi. Here, I post about programming to help developers.

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