UPC/3sem/data structures and algos/02/program.cpp

// dsaa_02.cpp
// Горбацевич Андрей
#include <iostream>
#include <map>
#include <vector>
#include <chrono>
#include <cmath>
#include <cassert>

#ifdef DEBUG
#define printf_d printf
#else
#define printf_d(...)
#endif

class DynIntArr {  // ngl, can be done better
private:
    int *container;
    int _size = 0;
    int _capacity;

    void _resize(int new_size) {
        int *new_container = new int [new_size];
        for (int i = 0; i < this->_size; i++) {
            *(new_container + i) = *(this->container + i);
        }
        std::swap(this->container, new_container);
        delete [] new_container;

        this->_capacity = new_size;
    }
public:
    explicit DynIntArr(int initial_size=8) {
        this->_capacity = initial_size;
        this->container = new int [this->_capacity]{0};
    }
    ~DynIntArr() {
        if (this->container != nullptr) {
            delete [] this->container;
        }
    }

    int &at(int pos) {
        if (pos < 0  || pos > this->_capacity) {
            throw std::runtime_error("Illegal array access");
        }
        return *(this->container + pos);
    }

    void add(int val) {
        if (this->_size+1 > this->_capacity) {
            this->_resize(this->_capacity*2);
        }
        this->at(this->_size++) = val;
    }

    int size() const {  // NOLINT(modernize-use-nodiscard)
        return this->_size;
    }

    int capacity() const {  // NOLINT(modernize-use-nodiscard)
        return this->_capacity;
    }
};

inline void time_passed(std::chrono::system_clock::time_point start, double &holder) {
    auto stop = std::chrono::high_resolution_clock::now();
    auto duration = std::chrono::duration_cast<std::chrono::microseconds>(stop - start);
    holder = duration.count();
}


void algo_01(DynIntArr &cont);  // algo with my container
void algo_02(std::vector<int> &cont);  // algo with stl's vector


// let's assume we are not including reading of data into algo's time
// 'cause it can at worst be O(inf)
int main() {
    int reserve = 50;
    DynIntArr dyn_arr(reserve);
    std::vector<int> vec_int;
    vec_int.reserve(reserve);

    int N = 0;
    std::cout << "N=";
    std::cin >> N;
    for (int i = 0; i < N; i++) {
        int num = 0;
        std::cin >> num;
        dyn_arr.add(num);
        vec_int.push_back(num);
    }

    double fft, sft = fft = 0;

    if (N <= 2) {  // Well, even if smth. is missed there is no way to determine
        goto endo;
    }

    {  // algo with my container
        auto start = std::chrono::high_resolution_clock::now();
        algo_01(dyn_arr);
        time_passed(start, fft);
    }
    {  // algo with stl's vector
        auto start = std::chrono::high_resolution_clock::now();
        algo_02(vec_int);
        time_passed(start, sft);
    }
    {  // let's check integrity of content
        assert(dyn_arr.size() == vec_int.size());
        for (int i = 0; i < dyn_arr.size(); i++) {
            assert(dyn_arr.at(i) == vec_int.at(i));
        }
    }

    endo:

    std::cout << "Fixed list: ";
    for (int i = 0; i < vec_int.size(); i++) {
        std::cout <<  vec_int.at(i) << " ";
    }
    std::cout << std::endl;

    printf(
            "algo_01 is %s than algo_02 by %.0f microseconds",
            (fft > sft? "slower" : "faster"), fabs(fft - sft)
    );

    return 0;
}

void algo_01(DynIntArr &cont) {
    if (cont.size() <= 2) {  // See this_file:97
        return;
    }

    int step = (cont.at(cont.size()-1) - cont.at(0)) / (cont.size() - 1);
    int miss_pos = -1;
    for (int i = 1; i < cont.size(); i++) {
        int p = cont.at(i - 1),
                c = cont.at(i);

        if (c - p != step) {
            miss_pos = i;
            break;
        }
    }

    if (miss_pos != -1) {
        int val = cont.at(0) - step;
        int elc = cont.size() + 1;
        cont = DynIntArr(cont.size() + 1);
        for (int i = 0; i < elc; i++) {
            cont.add(val += step);
        }
    }
}

void algo_02(std::vector<int> &cont) {
    if (cont.size() <= 2) {  // See this_file:97
        return;
    }

    int step = (cont.at(cont.size()-1) - cont.at(0)) / (cont.size() - 1);
    int miss_pos = -1;
    for (int i = 1; i < cont.size(); i++) {
        int p = cont.at(i - 1),
                c = cont.at(i);

        if (c - p != step) {
            miss_pos = i;
            break;
        }
    }

    if (miss_pos != -1) {
        int val = cont.at(0) - step;
        int elc = cont.size() + 1;
        cont.clear();
        for (int i = 0; i < elc; i++) {
            cont.push_back(val += step);
        }
    }
}


// Задана арифметическая прогрессия с одним пропущенным элементом.
// Выявить пропущенное и восстановить его в положенном месте.