Лаба 10

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

struct Node {
    string value;
    Node *next;

    Node(string _value, Node *_next = nullptr)
        : value(_value), next(_next) {}
};

struct List {
    Node *root = nullptr;

    string toString() {
        Node *current = this->root;
        ostringstream sstream;
        sstream << "[";
        if (current == nullptr) {
            sstream << "]";
        }
        while (current != nullptr) {
            sstream << current->value;
            current = current->next;
            if (current == nullptr) {
                sstream << "]";
            } else {
                sstream << ", ";
            }
        }
        return sstream.str();
    }

    int length() {
        int length = 0;
        Node *current = this->root;
        while (current != nullptr) {
            length++;
            current = current->next;
        }
        return length;
    }

    Node* last() {
        Node *current = this->root;
        while (current != nullptr) {
            if (current->next == nullptr) {
                return current;
            }
            current = current->next;
        }
        return nullptr;
    }

    void add(string value) {
        Node *_new = new Node(value);
        Node *last = this->last();
        if (last == nullptr) {
            this->root = _new;
        } else {
            last->next = _new;
        }
    }

    Node* nodeAt(int index) {
        Node* current = this->root;
        for (
            int i = 0;
            i != index && current != nullptr;
            i++, current = current->next
        );
        return current;
    }

    Node* findNode(string value) {
        Node* current = this->root;
        for (;
            current != nullptr && current->value != value;
            current = current->next
        );
        return current;
    }

    // Задание 1-Н
    void removeAllAfter(string value) {
        Node* node = this->findNode(value);
        if (node != nullptr) {
            node->next = nullptr;
        }
    }

    // Задание 2-А
    void replaceAt(int k, string value) {
        Node* node = this->nodeAt(k);
        if (node != nullptr) {
            node->value = value;
        }
    }

    // Задание 3-А
    int countStartingWith(char letter) {
        int count = 0;
        for (
            Node* current = this->root;
            current != nullptr;
            current = current->next
        ) {
            if (current->value[0] == letter) {
                count++;
            }
        }
        return count;
    }

    // Задание 4-В
    string* toArray(int k) {
        string* arr = new string[k];
        Node* current = this->root;
        for (
            int i = 0;
            i < k && current != nullptr;
            i++, current = current->next
        ) {
            arr[i] = current->value;
        }
        return arr;
    }
};

int main() {
    List list;

    list.add("ABC");
    list.add("ACD");
    list.add("DBC");
    list.add("BCD");
    list.add("XYZ");

    cout << list.toString() << " [" << list.length() << "]" << endl;

    list.removeAllAfter("DBC");

    cout << list.toString() << " [" << list.length() << "]" << endl;

    list.replaceAt(2, "dbc");

    cout << list.toString() << " [" << list.length() << "]" << endl;

    cout << "Starting with A: " << list.countStartingWith('A') << endl;

    string* arr = list.toArray(2);

    for (int i = 0; i < 2; i++) {
        cout << "> [" << i << "]: " << arr[i] << endl;
    }
};