lesson18_321

#include <iostream>

using namespace std;

double test(double a, double b, double c,
    double x) {
    return a * x * x + b * x + c;
}

void sqr_equation() {
    double a = 2, b = 4, c = -7;
    double d = b * b - 4 * a * c;
    cout << d << " " << sqrt(d) << endl;

    double x1 = 1.12132;
    double x2 = -3.12132;

    cout << test(a, b, c, x1) << " "
        << test(a, b, c, x2) << endl;
}

int arr[6]{ 3, 5, 7, 9, 11, 25647454 };

int summ_arr(int size, int arr[]) {
    int sum = 0;
    for (int k = 0; k < size; k++) {
        sum += arr[k];
    }
    return sum;
}

void sum_arr() {

    int sz1 = size(arr);
    int sz2 = sizeof(arr) / sizeof(arr[0]);
    cout << sz1 << " " << sz2 << endl;

    for (int k = 0; k < sz1; k++) {
        //arr[k] = 3 + 2 * k;
    }

    for (int k = 0; k < sz1; k++) {
        cout << arr[k] << " ";
    }
    cout << endl;

    int sum{ 0 }; // sum = 0;
    for (int k = 0; k < sz1; k++) {
        sum += arr[k];
    }
    cout << "sum: " << sum << endl;
}

int get_rand(int a, int b) {
    return rand() % (b - a + 1) + a;
}

void gen_arr(int size, int arr[]) {
    for (int k = 0; k < size; k++) {
        arr[k] = get_rand(-10, 10);
    }
}

void show_arr(int size, int arr[]) {
    for (int k = 0; k < size; k++) {
        cout << arr[k] << " ";
    }
    cout << endl;
}

int product_even(int size, int arr[]) {
    int prod = 1;
    int start = 0;
    int finish = 0;

    for (int k = 0; k < size; k++) {
        if (arr[k] < 0) {
            start = k;
            break;
        }
    }

    for (int k = size - 1; k >= 0; k--) {
        if (arr[k] < 0) {
            finish = k;
            break;
        }
    }

    if (finish <= start) {
        cout << "All are positive or only one negative, may be...\n";
        return 0;
    }

    for (int k = start; k <= finish; k++) {
        if ((arr[k] % 2 == 0) && (arr[k] != 0)) {
            prod *= arr[k];
        }
    }

    cout << start << " " << finish << endl;
    return prod;
}

void task_aa() {
    int arr[10];
    gen_arr(size(arr), arr);
    arr[5] = 0;
    show_arr(size(arr), arr);
    cout << "prod: " << product_even(size(arr), arr);
}

void test_arr2D() {
    const int sz1 = 3;
    const int sz2 = 4;
    int arr[sz1][sz2]{{1, 2, 3, 4},
                      {5, 6, 7, 8},
                      {9,10,11,12}};

    cout << arr[1][3] << endl;

    for (int k = 0; k < sz1; k++) {
        for (int n = 0; n < sz2; n++) {
            cout << arr[k][n] << "\t";
        }
        cout << endl;
    }

    cout << endl;
    for (int k = 0; k < sz2; k++) {
        for (int n = 0; n < sz1; n++) {
            cout << arr[n][k] << "\t";
        }
        cout << endl;
    }


}

void main() {
    srand(time(NULL));

    test_arr2D();

    //task_aa();
    //sum_arr();
}