#include <iostream>
#include <cassert>
#include <string>
#include <vector>
#include <ctime>
#include <random>
#include <cmath>


class Str {
    char* data = nullptr;
    unsigned max_capacity;
    unsigned cur_length;

    void extend() {
        max_capacity *= 2;
        char* buf = new char[max_capacity];
        char* runner = data;
        int pos = 0;
        while (*runner) {
            buf[pos] = *runner;
            runner++;
            pos++;
        }
        delete data;
        data = buf;
    }

    void add(char c) {
        if (cur_length == max_capacity) {
            extend();
        }
        data[cur_length++] = c;
    }

    void add_c_str(const char * str) {

        while (*str) {
            add(*str);
            str++;
        }
    }

public:

    Str() {
        max_capacity = 200;
        data = new char[max_capacity];
        cur_length = 0;
    }

    ~Str() {
        if (data != nullptr) {
            delete data;
        }
    }

    Str& operator << (const char* value) {
        add_c_str(value);
        return *this;
    }
    Str& operator << (const std::string& s) {
        add_c_str(s.c_str());
        return *this;
    }


    operator const char* () {
        add('\0');
        return data;
    }

};

class Str_v {

    std::vector<char> data;


    void add(char c) {
        data.push_back(c);
    }

    void add_c_str(const char * str) {

        while (*str) {
            add(*str);
            str++;
        }
    }

public:

    Str_v& operator << (const char* value) {
        add_c_str(value);
        return *this;
    }
    Str_v& operator << (const std::string& s) {
        add_c_str(s.c_str());
        return *this;
    }


    operator const char* () {
        add('\0');
        const auto r = &data[0];
        return r;
    }

};

int main() {

    size_t str_len = 5;
    size_t len;

    int count = 15;

    while (--count > 0) {

        // Preparing data
        std::vector<std::string> data;
        for (int i = 0; i < str_len; ++i) {
            std::string data_str;
            len = (int)std::sqrt(str_len);
            for (int j = 0; j < len; ++j) {
                data_str.push_back('a' + std::rand() % 26);
            }
            data.push_back(data_str);
        }

        clock_t begin = clock();

        Str_v str_v;
        for (const auto& vx : data) {
            str_v << vx << " ";
        }
        const char * data_v = str_v;

        clock_t end = clock();
        double elapsed_secs_v = double(end - begin) / CLOCKS_PER_SEC;



        begin = clock();

        Str str;
        for (const auto& vx : data) {
            str << vx << " ";
        }
        const char * data_p = str;

        end = clock();
        double elapsed_secs = double(end - begin) / CLOCKS_PER_SEC;

        int equality = strcmp(data_v, data_p);

        std::cout << "Time for " << str_len << " strings with " << len << "symbols: pointers = " << elapsed_secs << ", vectors = " << elapsed_secs_v << ". Equality: " << equality << '\n';
        //std::cout << "Data: " << data2 << "\n\n";


        str_len *= 2;
    }

    return 0;
}