advent2023

commit de89cfa39333a782338aff416883dbbd827c4209
parent cd360b8395d441a8a5cff9f379ff63bc14bb5f31
Author: bsandro <email@bsandro.tech>
Date:   Sat, 16 Dec 2023 18:39:49 +0200

day 16 p2 or "I really needed some sort of hashmaps here"

Diffstat:
M
day16/Makefile
 | 
2
+-
M
day16/puzzle.c
 | 
73
+++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------

2 files changed, 54 insertions(+), 21 deletions(-)
diff --git a/day16/Makefile b/day16/Makefile
@@ -2,7 +2,7 @@ NAME=$(shell basename ${PWD})
 SRC=$(wildcard *.c)
 DEPS:=$(wildcard *.h)
 OBJ:=$(SRC:.c=.o)
-CFLAGS=-O0 -g -std=c11 -Werror -Wall -Wextra -I. -I../common
+CFLAGS=-O2 -std=c11 -Werror -Wall -Wextra -I. -I../common
 LDFLAGS=-lc
 
 all: $(NAME)
diff --git a/day16/puzzle.c b/day16/puzzle.c
@@ -63,6 +63,11 @@ bool visited_has(Visited *visited, Pos p) {
 	return false;
 }
 
+void visited_destroy(Visited *visited) {
+	//@todo
+	(void)visited;
+}
+
 Pos get_next_empty(Pos cur) {
 	Pos p = cur;
 	switch (cur.dir) {
@@ -237,6 +242,32 @@ void traverse(Map *map, Map *energized, Visited *visited, Pos start) {
 	}
 }
 
+long long count_energized(Map *map) {
+	long long result = 0;
+	Map energized = {0};
+	energized.size = map->size;
+	energized.w = map->w;
+	energized.h = map->h;
+	energized.area = malloc(energized.size);
+	memset(energized.area, '.', energized.size);
+
+	Visited visited = {0};
+	traverse(map, &energized, &visited, map->start);
+
+	for (int y=0; y<energized.h; ++y) {
+		for (int x=0; x<energized.w; ++x) {
+			if (energized.area[y*energized.w+x]=='#') {
+				result++;
+			}
+		}
+	}
+
+	free(energized.area);
+	visited_destroy(&visited);
+
+	return result;
+}
+
 void puzzle(const char *filename, long long *result1, long long *result2) {
 	FILE *infile = fopen(filename, "r");
 	if (infile == NULL) {
@@ -260,33 +291,35 @@ void puzzle(const char *filename, long long *result1, long long *result2) {
 		bzero(buf, STR_LEN);
 	}
 	map.h = line_num;
+
 	map.start = (Pos){.x=0,.y=0,.dir=DIR_RIGHT};
+	*result1 = count_energized(&map);
+	*result2 = 0;
 
-	Map energized = {0};
-	energized.size = map.size;
-	energized.w = map.w;
-	energized.h = map.h;
-	energized.area = malloc(energized.size);
-	memset(energized.area, '.', energized.size);
+	for (int x=0; x<map.w; ++x) {
+		// top row
+		map.start = (Pos){.x=x,.y=0,.dir=DIR_DOWN};
+		long long res = count_energized(&map);
+		if (res>*result2) *result2 = res;
 
-	Visited visited = {0};
+		// bottom row
+		map.start = (Pos){.x=x,.y=map.h-1,.dir=DIR_UP};
+		res = count_energized(&map);
+		if (res>*result2) *result2 = res;
+	}
 
-	traverse(&map, &energized, &visited, map.start);
+	for (int y=0; y<map.h; ++y) {
+		// leftmost column
+		map.start = (Pos){.x=0,.y=y,.dir=DIR_RIGHT};
+		long long res = count_energized(&map);
+		if (res>*result2) *result2 = res;
 
-	*result1 = 0;
-	printf("energized %dx%d:\n", energized.w, energized.h);
-	for (int y=0; y<energized.h; ++y) {
-		for (int x=0; x<energized.w; ++x) {
-			//printf("%c", energized.area[y*energized.w+x]);
-			if (energized.area[y*energized.w+x]=='#') {
-				(*result1)++;
-			}
-		}
-		//printf("\n");
+		// rightmost column
+		map.start = (Pos){.x=map.w-1,.y=y,.dir=DIR_RIGHT};
+		res = count_energized(&map);
+		if (res>*result2) *result2 = res;
 	}
 
 	// mutiny! ignoring feof/ferror.
 	fclose(infile);
-	(void)result1;
-	(void)result2;
 }