commit 6aef118d598a26b339a578dd83e6dbb09366bacd
parent 99aed221f29a7174d0cddebc9003dbc6779b3d0d
Author: bsandro <brian.drosan@gmail.com>
Date: Sun, 5 Dec 2021 16:12:14 +0200
Day 05, puzzle 2
Diffstat:
M | day05/puzzle.c | | | 105 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------- |
1 file changed, 77 insertions(+), 28 deletions(-)
diff --git a/day05/puzzle.c b/day05/puzzle.c
@@ -15,7 +15,8 @@
#define MAP_SIZE 1000
// being tad lazy here - assume that the map sides are no larger than MAP_SIZE
-static short map[MAP_SIZE][MAP_SIZE];
+static short map1[MAP_SIZE][MAP_SIZE];
+static short map2[MAP_SIZE][MAP_SIZE];
struct vec2_t {
int x;
@@ -32,8 +33,10 @@ struct vec2_pair_t make_pair(const char *str);
struct vec2_t make_vec2(const char *str);
void swap_vec2(struct vec2_t *a, struct vec2_t *b); // swap a and b
void print_pair(const struct vec2_pair_t *pair);
+bool is_pair_diagonal(const struct vec2_pair_t *pair);
void normalize_pair(struct vec2_pair_t *pair); // ensure begin is always smaller number
-int mark_map(const struct vec2_pair_t *pair);
+int mark_map1(const struct vec2_pair_t *pair);
+int mark_map2(const struct vec2_pair_t *pair);
void print_map();
/* ****************************************************************** */
@@ -47,15 +50,17 @@ void puzzle(const char *filename, int *result1, int *result2) {
char buf[STR_LEN] = {0};
unsigned int line_num = 0;
- int danger_points = 0;
+
+ *result1 = 0;
+ *result2 = 0;
while (fgets(buf, STR_LEN, infile) != NULL) {
struct vec2_pair_t pair = make_pair(buf);
- // only straight lines
- if (pair.a.x == pair.b.x || pair.a.y == pair.b.y) {
+ // only straight and 45deg diagonal lines
+ if (pair.a.x == pair.b.x || pair.a.y == pair.b.y || is_pair_diagonal(&pair)) {
normalize_pair(&pair);
- //print_pair(&pair);
- danger_points += mark_map(&pair);
+ *result1 += mark_map1(&pair);
+ *result2 += mark_map2(&pair);
}
++line_num;
@@ -64,9 +69,6 @@ void puzzle(const char *filename, int *result1, int *result2) {
//print_map();
- *result1 = danger_points;
- *result2 = 0;
-
// mutiny! ignoring feof/ferror.
fclose(infile);
}
@@ -125,10 +127,10 @@ void print_map() {
printf("\n--------MAP-----------\n");
for (int y = 0; y < MAP_SIZE; ++y) {
for (int x = 0; x < MAP_SIZE; ++x) {
- if (map[x][y] == 0) {
+ if (map2[x][y] == 0) {
printf(".");
} else {
- printf("%d", map[x][y]);
+ printf("%d", map2[x][y]);
}
}
printf("\n");
@@ -136,36 +138,83 @@ void print_map() {
printf("\n-----------------------\n");
}
+bool is_pair_diagonal(const struct vec2_pair_t *pair) {
+ return abs(pair->a.x - pair->b.x) == abs(pair->a.y - pair->b.y);
+}
+
void normalize_pair(struct vec2_pair_t *pair) {
- if (pair->a.x == pair->b.x) {
- if (pair->a.y > pair->b.y) {
- swap_vec2(&pair->a, &pair->b);
+ if (pair->a.x == pair->b.x && pair->a.y > pair->b.y) {
+ // straight verticals
+ swap_vec2(&pair->a, &pair->b);
+ } else if (pair->a.y == pair->b.y && pair->a.x > pair->b.x) {
+ // straight horizontals
+ swap_vec2(&pair->a, &pair->b);
+ } else if (is_pair_diagonal(pair) && pair->a.x > pair->b.x) {
+ // normalize diagonals only by x axis
+ swap_vec2(&pair->a, &pair->b);
+ }
+}
+
+int mark_map1(const struct vec2_pair_t *pair) {
+ int count = 0;
+
+ if (pair->a.x == pair->b.x) { // vertical lines
+ int x = pair->a.x;
+ for (int y = pair->a.y; y <= pair->b.y; ++y) {
+ if (++map1[x][y] == 2) {
+ ++count;
+ }
}
- } else if (pair->a.y == pair->b.y) {
- if (pair->a.x > pair->b.x) {
- swap_vec2(&pair->a, &pair->b);
+ } else if (pair->a.y == pair->b.y) { // horizontal lines
+ int y = pair->a.y;
+ for (int x = pair->a.x; x <= pair->b.x; ++x) {
+ if (++map1[x][y] == 2) {
+ ++count;
+ }
}
}
+
+ return count;
}
-int mark_map(const struct vec2_pair_t *pair) {
- int sum = 0;
- // @todo tidy up?
- if (pair->a.x == pair->b.x) {
+int mark_map2(const struct vec2_pair_t *pair) {
+ int count = 0;
+
+ if (pair->a.x == pair->b.x) { // vertical lines
int x = pair->a.x;
for (int y = pair->a.y; y <= pair->b.y; ++y) {
- if (++map[x][y] == 2) { // only counting each overlap once
- ++sum;
+ if (++map2[x][y] == 2) {
+ ++count;
}
}
- } else if (pair->a.y == pair->b.y) {
+ } else if (pair->a.y == pair->b.y) { // horizontal lines
int y = pair->a.y;
for (int x = pair->a.x; x <= pair->b.x; ++x) {
- if (++map[x][y] == 2) {
- ++sum;
+ if (++map2[x][y] == 2) {
+ ++count;
+ }
+ }
+ } else if (is_pair_diagonal(pair)) { // diagonal lines
+ int x = pair->a.x;
+ int y = pair->a.y;
+ if (pair->a.y < pair->b.y) {
+ for (; x <= pair->b.x && y <= pair->b.y;) {
+ if (++map2[x][y] == 2) {
+ ++count;
+ }
+ ++x;
+ ++y;
+ }
+ } else {
+ for (; x <= pair->b.x && y >= pair->b.y;) {
+ if (++map2[x][y] == 2) {
+ ++count;
+ }
+ ++x;
+ --y;
}
}
}
- return sum;
+ return count;
}