AOC 2024/10

1 files changed, 177 insertions, 0 deletions

diff --git a/2024/10/1.c b/2024/10/1.c
new file mode 100644
index 0000000..a8112a6
--- /dev/null
+++ b/2024/10/1.c
@@ -0,0 +1,177 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include "../../d.h"
+#include "map.h"
+
+bool debug = true;
+
+typedef struct {
+	int	width;
+	int	height;
+	char**	e;
+	bool**	visited;
+} Graph2D;
+
+enum {
+	NORTH = 0, EAST, SOUTH, WEST, DIRECTIONS,
+};
+
+/* Reads from the input until exhausted. Returns memory which must be
+freed by the caller. */
+Graph2D*
+ingest(FILE* in)
+{
+	char *t = getall(in);
+	char *s = t;
+
+	/* Two passes. One to count width and height.
+		Another to store to allocated memory. */
+	int height = 0, width = -1, i = 0;
+	while (s[i] != '\0') {
+		if (s[i] == '\n') {
+			if (width == -1) {
+				width = i + 1; 
+			}
+			height++;
+		}
+		i++;
+	}
+	char** buffer = calloc(height, sizeof(char*));
+	bool** visited = calloc(height, sizeof(bool*));
+
+	Graph2D* g = calloc(1, sizeof(Graph2D));
+	g->width = width;
+	g->height = height;
+	g->e = buffer;
+	g->visited = visited;
+	
+	i = height;
+	while (i > 0) {
+		buffer[i-1] = calloc(width, sizeof(char));
+		visited[i-1] = calloc(width, sizeof(bool));
+		i--;
+	}
+
+	i = 0;
+	int j = 0;
+	while (i < height) {
+		if (j < width - 1) {
+			buffer[i][j] = *s;
+			j++;
+		} else {
+			i++;
+			j = 0;
+		}
+		s++;
+	}
+	
+	free(t);
+	return g;
+}
+
+typedef struct {
+	int	x;
+	int	y;
+} Coordinates;
+
+typedef struct Stack {
+	void*		value;
+	struct Stack*	below;
+} Stack;
+
+Stack*
+pop(Stack* s) {
+	free(s->value);
+	Stack* tmp = s->below;
+	free(s);
+	return tmp;
+}
+Stack*
+push(Stack* s, void* value) {
+	Stack* t = calloc(1, sizeof(Stack));
+	t->below = s;
+	t->value = value;
+	return t;
+}
+
+bool
+valid(Graph2D* g, Coordinates c)
+{
+	return c.x >= 0 && c.x < g->width && c.y >= 0 && c.y < g->height;
+}
+
+int score = 0;
+void
+travel(Graph2D* g, Coordinates c)
+{
+	// g->visited[c.y][c.x] = true;
+
+	if (debug) {
+		printf("%d,%d\n", c.x, c.y);
+		printf("%c\n", g->e[c.y][c.x]);
+	}
+
+	Coordinates cardinal[DIRECTIONS];
+	cardinal[SOUTH] = (Coordinates) {c.x, c.y + 1};
+	cardinal[NORTH] = (Coordinates) {c.x, c.y - 1};
+	cardinal[EAST] = (Coordinates) {c.x + 1, c.y};
+	cardinal[WEST] = (Coordinates) {c.x - 1, c.y};
+
+	if (g->e[c.y][c.x] == '9') {
+		score++;
+		return;
+	}
+	for (int i = 0; i < DIRECTIONS; i++) {
+		if (valid(g, cardinal[i])) {
+			if (debug) {
+				printf("%d,%d\n", cardinal[i].x, cardinal[i].y);
+				printf("%d\n", g->e[cardinal[i].y][cardinal[i].x]);
+				printf("-\n");
+				printf("%d\n", g->e[c.y][c.x]);
+				printf("%d\n", g->e[cardinal[i].y][cardinal[i].x] - g->e[c.y][c.x]);
+			}
+
+			if (g->e[cardinal[i].y][cardinal[i].x] - g->e[c.y][c.x] == 1) {
+				if (debug) {
+					printf("Valid: %d,%d\n", cardinal[i].x, cardinal[i].y);
+				}
+				travel(g, cardinal[i]);
+			}
+		}
+	}
+	return;
+}
+
+int
+main()
+{
+	FILE* in = fopen("sample_small", "r");
+	if (in == NULL) {
+		exit(1);
+	}
+
+	Graph2D* g = ingest(in);
+
+	for (int i = 0; i < g->height; i++) {
+		for (int j = 0; j < g->width; j++) {
+			if (g->e[i][j] == '0') {
+				travel(g, (Coordinates) {j, i});
+				// Score is a global
+				printf("%d\n", score);
+			}
+		}
+	}
+	
+	for (int i = 0; i < g->height; i++) {
+		for (int j = 0; j < g->width; j++) {
+			printf("%c", g->e[i][j]);
+		}
+		putchar('\n');
+		free(g->e[i]);
+		free(g->visited[i]);
+	}
+	free(g->e);
+	free(g->visited);
+	free(g);
+	return 0;
+}