#include "n_queens.h"

void	print_number(int n)
{
	char	c;

	if (n >= 10)
		print_number(n / 10);
	c = '0' + (n % 10);
	write(1, &c, 1);
}

void	print_solution(int *queens, int n)
{
	int	i;

	i = 0;
	while (i < n)
	{
		if (i > 0)
			write(1, " ", 1);
		print_number(queens[i]);
		i++;
	}
	write(1, "\n", 1);
}

int	is_safe(int *queens, int row, int col, int n)
{
	int	i;

	(void)n;
	i = 0;
	while (i < row)
	{
		if (queens[i] == col)
			return (0);
		if (queens[i] - i == col - row)
			return (0);
		if (queens[i] + i == col + row)
			return (0);
		i++;
	}
	return (1);
}

void	solve_nqueens(int *queens, int row, int n)
{
	int	col;

	if (row == n)
	{
		print_solution(queens, n);
		return ;
	}
	col = 0;
	while (col < n)
	{
		if (is_safe(queens, row, col, n))
		{
			queens[row] = col;
			solve_nqueens(queens, row + 1, n);
		}
		col++;
	}
}

int	main(int argc, char **argv)
{
	int	n;
	int	*queens;

	if (argc != 2)
		return (1);
	n = atoi(argv[1]);
	if (n <= 0)
		return (1);
	queens = (int *)malloc(sizeof(int) * n);
	if (!queens)
		return (1);
	solve_nqueens(queens, 0, n);
	free(queens);
	return (0);
}