16.cpp

/*A Dictionary stores keywords & its meanings. Provide facility for adding new keywords, 
Deleting keywords, updating values of any entry. Provide facility to display whole data sorted
in ascending/ Descending order. Also find how many maximum comparisons may require for finding
any keyword. Use Height balance tree (AVL) and find the complexity for finding a keyword*/

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

struct Node {
    string keyword, meaning;
    Node *left = nullptr, *right = nullptr;
    int height = 1;
};

int height(Node* node) {
    return node ? node->height : 0;
}

int max(int a, int b) {
    return (a > b) ? a : b;
}

Node* newNode(string keyword, string meaning) {
    return new Node{keyword, meaning};
}

int getBalance(Node* N) {
    return N ? height(N->left) - height(N->right) : 0;
}

Node* rightRotate(Node* y) {
    Node* x = y->left;
    Node* T2 = x->right;
    x->right = y;
    y->left = T2;
    y->height = max(height(y->left), height(y->right)) + 1;
    x->height = max(height(x->left), height(x->right)) + 1;
    return x;
}

Node* leftRotate(Node* x) {
    Node* y = x->right;
    Node* T2 = y->left;
    y->left = x;
    x->right = T2;
    x->height = max(height(x->left), height(x->right)) + 1;
    y->height = max(height(y->left), height(y->right)) + 1;
    return y;
}

Node* insert(Node* node, string keyword, string meaning) {
    if (!node) return newNode(keyword, meaning);
    if (keyword < node->keyword)
        node->left = insert(node->left, keyword, meaning);
    else if (keyword > node->keyword)
        node->right = insert(node->right, keyword, meaning);
    else
        node->meaning = meaning;
    node->height = 1 + max(height(node->left), height(node->right));
    int balance = getBalance(node);
    if (balance > 1 && keyword < node->left->keyword) return rightRotate(node);
    if (balance < -1 && keyword > node->right->keyword) return leftRotate(node);
    if (balance > 1 && keyword > node->left->keyword) {
        node->left = leftRotate(node->left);
        return rightRotate(node);
    }
    if (balance < -1 && keyword < node->right->keyword) {
        node->right = rightRotate(node->right);
        return leftRotate(node);
    }
    return node;
}

Node* minValueNode(Node* node) {
    Node* current = node;
    while (current->left)
        current = current->left;
    return current;
}

Node* deleteNode(Node* root, string keyword) {
    if (!root) return root;
    if (keyword < root->keyword)
        root->left = deleteNode(root->left, keyword);
    else if (keyword > root->keyword)
        root->right = deleteNode(root->right, keyword);
    else {
        if (!root->left || !root->right) {
            Node* temp = root->left ? root->left : root->right;
            if (!temp) {
                temp = root;
                root = nullptr;
            } else
                *root = *temp;
            delete temp;
        } else {
            Node* temp = minValueNode(root->right);
            root->keyword = temp->keyword;
            root->meaning = temp->meaning;
            root->right = deleteNode(root->right, temp->keyword);
        }
    }
    if (!root) return root;
    root->height = 1 + max(height(root->left), height(root->right));
    int balance = getBalance(root);
    if (balance > 1 && getBalance(root->left) >= 0) return rightRotate(root);
    if (balance > 1 && getBalance(root->left) < 0) {
        root->left = leftRotate(root->left);
        return rightRotate(root);
    }
    if (balance < -1 && getBalance(root->right) <= 0) return leftRotate(root);
    if (balance < -1 && getBalance(root->right) > 0) {
        root->right = rightRotate(root->right);
        return leftRotate(root);
    }
    return root;
}

string search(Node* root, string keyword, int& comparisons) {
    Node* current = root;
    while (current) {
        comparisons++;
        if (keyword == current->keyword) return current->meaning;
        else if (keyword < current->keyword) current = current->left;
        else current = current->right;
    }
    return "Keyword not found";
}

void traverseInOrder(Node* root) {
    if (root) {
        traverseInOrder(root->left);
        cout << root->keyword << ": " << root->meaning << endl;
        traverseInOrder(root->right);
    }
}

void traverseInOrderReverse(Node* root) {
    if (root) {
        traverseInOrderReverse(root->right);
        cout << root->keyword << ": " << root->meaning << endl;
        traverseInOrderReverse(root->left);
    }
}

int main() {
    Node* root = nullptr;
    int choice, comparisons;
    string keyword, meaning;
    do {
        cout << "\nAVL Dictionary\n1. Insert\n2. Delete\n3. Search\n4. Ascending\n5. Descending\n6. Exit\nChoice: ";
        cin >> choice;
        switch (choice) {
            case 1:
                cout << "Keyword to insert: "; cin >> keyword;
                cout << "Meaning: "; cin.ignore(); getline(cin, meaning);
                root = insert(root, keyword, meaning);
                break;
            case 2:
                cout << "Keyword to delete: "; cin >> keyword;
                root = deleteNode(root, keyword);
                break;
            case 3:
                cout << "Keyword to search: "; cin >> keyword; comparisons = 0;
                meaning = search(root, keyword, comparisons);
                cout << "Meaning: " << meaning << "\nComparisons: " << comparisons << endl;
                break;
            case 4: cout << "Ascending:\n"; traverseInOrder(root); break;
            case 5: cout << "Descending:\n"; traverseInOrderReverse(root); break;
            case 6: cout << "Exiting...\n"; break;
            default: cout << "Invalid choice.\n";
        }
    } while (choice != 6);
    return 0;
}