From: Lukáš Jiřiště <gymnazium.jiriste@gmail.com>
Date: Mon, 4 Dec 2023 17:50:49 +0000 (+0100)
Subject: Add solution to second part of day 3
X-Git-Url: https://git.ljiriste.work/?a=commitdiff_plain;h=03b436039845be4aa342d71f3c26b508ec58efec;p=AoC_2023.git

Add solution to second part of day 3
---

diff --git a/3/3b.c b/3/3b.c
new file mode 100644
index 0000000..8a675ea
--- /dev/null
+++ b/3/3b.c
@@ -0,0 +1,190 @@
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "libft.h"
+
+struct s_matrix
+{
+	size_t	rows;
+	size_t	cols;
+	char	*array;
+};
+typedef struct s_matrix	t_matrix;
+
+char	*get_element(t_matrix matrix, size_t i, size_t j)
+{
+	if (i >= matrix.rows || j >= matrix.cols)
+		return (NULL);
+	return (matrix.array + i * matrix.cols + j);
+}
+
+int	fill_matrix_size(t_matrix *matrix, const char *file_name)
+{
+	int		fd;
+	char	c;
+	char	*line;
+
+	matrix->rows = 1;
+	matrix->cols = 0;
+	fd = open(file_name, O_RDONLY);
+	if (fd < 0)
+		return (-1);
+	c = 'a';
+	while (c != '\n' && c != '\0')
+	{
+		read(fd, &c, 1);
+		++matrix->cols;
+	}
+	--matrix->cols;
+	line = malloc(matrix->cols + 1);
+	while (read(fd, line, matrix->cols + 1))
+		++matrix->rows;
+	close(fd);
+	free(line);
+	return (0);
+}
+
+t_matrix	read_as_matrix(const char *file_name)
+{
+	int			fd;
+	t_matrix	matrix;
+	size_t		i;
+	size_t		j;
+	char		*line;
+
+	fill_matrix_size(&matrix, file_name);
+	fd = open(file_name, O_RDONLY);
+	if (fd < 0)
+		return (matrix);
+	matrix.array = malloc(matrix.rows * matrix.cols * sizeof(*matrix.array));
+	if (!matrix.array)
+		return (matrix);
+	line = malloc(matrix.cols + 1);
+	i = 0;
+	while (i < matrix.rows)
+	{
+		read(fd, line, matrix.cols + 1);
+		j = 0;
+		while (j < matrix.cols)
+		{
+			*get_element(matrix, i, j) = line[j];
+			++j;
+		}
+		++i;
+	}
+	free(line);
+	return (matrix);
+}
+
+size_t	get_number_length(const char *number)
+{
+	size_t	result;
+
+	result = 0;
+	while (ft_isdigit(number[result]))
+		++result;
+	return (result);
+}
+
+int	serial_to_int(t_matrix schematics, size_t i, size_t j)
+{
+	char	*serial;
+	int		result;
+	size_t	length;
+	char	*el;
+
+	while (1)
+	{
+		el = get_element(schematics, i, j);
+		if (!el)
+			break;
+		if (!ft_isdigit(*el))
+			break;
+		--j;
+	}
+	++j;
+	el = get_element(schematics, i, j);
+	length = get_number_length(el);
+	serial = ft_strndup(el, length);
+	result = ft_atoi(serial);
+	free(serial);
+	return (result);
+}
+
+int	gear_ratio(t_matrix schematics, size_t i, size_t j)
+{
+	const size_t	i_0 = i;
+	const size_t	j_0 = j;
+	int				part[2];
+	size_t			k;
+	int				adjacent_digit;
+
+	k = 0;
+	if (i > 0)
+		--i;
+	while (i <= i_0 + 1)
+	{
+		adjacent_digit = 0;
+		j = j_0;
+		if (j > 0)
+			j = j_0 - 1;
+		while (j <= j_0 + 1)
+		{
+			if (get_element(schematics, i, j))
+			{
+				if (ft_isdigit(*get_element(schematics, i, j)) && !adjacent_digit)
+				{
+					if (k < 2)
+						part[k] = serial_to_int(schematics, i, j);
+					++k;
+					adjacent_digit = 1;
+				}
+				else if (!ft_isdigit(*get_element(schematics, i, j)))
+					adjacent_digit = 0;
+			}
+			++j;
+		}
+		++i;
+	}
+	if (k == 2)
+	{
+		ft_printf("Found pair by cogs: %i * %i = %i.\n", part[0], part[1], part[0] * part[1]);
+		return (part[0] * part[1]);
+	}
+	return (0);
+}
+
+int	process(t_matrix schematics)
+{
+	int		result;
+	size_t	i;
+	size_t	j;
+
+	result = 0;
+	i = 0;
+	while (i < schematics.rows)
+	{
+		j = 0;
+		while (j < schematics.cols)
+		{
+			if (*get_element(schematics, i, j) == '*')
+				result += gear_ratio(schematics, i, j);
+			++j;
+		}
+		++i;
+	}
+	return (result);
+}
+
+int	main(int argc, char **argv)
+{
+	t_matrix	schematics;
+
+	if (argc != 2)
+		return (1);
+	schematics = read_as_matrix(argv[1]);
+	ft_printf("The resulting sum is %i.\n", process(schematics));
+	return (0);
+}
+