//Матрицы
//19. По заданным коэффициентам и правым частям найти решение "треугольной" системы из n уравнений.

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <ctime>

double** create_array(int string, int column)
{
	double **a = new double*[string];
	for (unsigned int i = 0; i < string; i++)
	{
		a[i] = new double[column];
	}
	return a;
}

void delete_array(double **a, int string)
{
	for (int j = 0; j < string; j++)
		delete[]a[j];
}

void print_array(double **a, int string, int column)
{
	for (unsigned int k = 0; k < string; k++)
	{
		printf("\n");
		for (unsigned int j = 0; j < column; j++)
		{
			printf("%f\t", a[k][j]);
		}
	}
	printf("\n");
}
void fill_array(double **a, int string, int column)
{
	for (unsigned int k = 0; k < string; k++)
		for (unsigned int j = 0; j < column; j++)
		{
			if (j == column - 1 || j <= k)
				a[k][j] = rand() % 10 + 1;
			else
				a[k][j] = 0;
		}
}
double **find_solution(double **a, int string, int column)
{
	double **arr = create_array(string, 1);
	for (int i = 0; i < string; i++)
	{
		arr[i][0] = 0;
	}
	arr[0][0] = a[0][column - 1] / a[0][0];
	for (int i = 1; i < string; i++)
	{
		arr[i][0] += a[i][column - 1];
		for (int j = 0; j < i; j++)
		{
			arr[i][0] -= (a[i][j] * arr[j][0]);

		}
		arr[i][0] /= a[i][i];
	}
	return arr;
}


int main()
{
	int string;
	int column;
	srand(time(0));

	printf("put the number of unknowns, please:\n");
	scanf("%d", &string);
	column = string + 1;
	double **a = create_array(string, column);
	fill_array(a, string, column);
	printf("Matrix:");
	print_array(a, string, column);
	double **b = find_solution(a, string, column);
	printf("\nSolution:");
	print_array(b, string, 1);


	delete_array(a, string);
	delete_array(b, string);
	system("pause");
	return 0;
}