lab25

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstdarg>


class Matrix {
public:
    Matrix(int order, double **m) {
        this->order = order;
        this->m = m;
    }
    Matrix getMinor(int mi, int mj) {
        int order = this->order;
        double **table = create_table(order - 1);
        for (int i = 0, ti = 0; i < order; ++ i) {
            if (i != mi) {
                for (int j = 0, tj = 0; j < order; ++ j) {
                    if (j != mj) {
                        table[ti][tj] = this->m[i][j];
                        ++ tj;
                    }
                }
                ++ ti;
            }
        }
        return Matrix(order - 1, table);
    }
    double** getMatrix() {
        return this->m;
    }
    double getDet() {
        if (this->order != 2) {
            double a = 0;
            for (int i = 0; i < this->order; ++ i) {
                //printf("%f, m[%d][0] = %f\n", this->m[i][0] * this->getMinor(i, 0).getDet() * ((i % 2 != 0) ? -1 : 1), i, this->m[i][0]);
                a += this->m[i][0] * this->getMinor(i, 0).getDet() * ((i % 2 != 0) ? -1 : 1);
            }
            return a;
        }
        else
            return this->m[0][0] * this->m[1][1] - this->m[0][1] * this->m[1][0];
    }
    static double** create_table(int n) {
        double **table, *row;
        table = (double**)malloc(n * sizeof(double*));
        for (int i = 0; i < n; ++ i) {
            row = (double*)malloc(n * sizeof(double));
            table[i] = row;
        }
        return table;
    }

    static void copy_table(double **a, double **b, int n) { // a <- b
        for (int i = 0; i < n; ++ i)
            for (int j = 0; j < n; ++ j)
                a[i][j] = b[i][j];
    }

    static void change_column(double **a, int n, double *b, int column) {
        for (int i = 0; i < n; ++ i)
            a[i][column] = b[i];
    }

private:
    int order;
    double **m;
};

/*
void set_val(double **f, int n, ...) {
    va_list elem;
    va_start(elem, n);
    for (int i = 0; i < n; ++ i) {
        for (int j = 0; j < n; ++ j) {
            f[i][j] = va_arg(elem, double);
        }
    }
    va_end(elem);
}
*/

int main(void) {
    int n;
    printf("Введите количество линейных уравнений в системе> ");
    scanf("%d", &n);
    double **table = Matrix::create_table(n), **backup = Matrix::create_table(n);
    printf("Вводите коэффициэнты при каждой из переменных:\n");
    for (int i = 0; i < n; ++ i)
        for (int j = 0; j < n; ++ j)
            scanf("%lf", &table[i][j]);
    Matrix::copy_table(backup, table, n);
    printf("Вводите результаты уравнений:\n");
    double ans[n];
    for (int i = 0; i < n; ++ i)
        scanf("%lf", ans + i);

    Matrix m = Matrix(n, table);
    double det = m.getDet(), det_dop;
    if (det == 0) {
        printf("Главный определитель равен 0\n");
        return 0;
    }
    printf("Корни:\n");
    for (int i = 0; i < n; ++ i) {
        Matrix::change_column(table, n, ans, i);
        det_dop = m.getDet();
        printf("%f\n", det_dop / det);
        Matrix::copy_table(table, backup, n);
    }
    return 0;
}