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day 11 final (C)

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This commit is contained in:
Bruno Raoult
2021-12-12 19:37:31 +01:00
parent dbf9b52cb3
commit 9c5e734ece
5 changed files with 112 additions and 60 deletions
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2
2021/day11/Makefile
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@@ -24,7 +24,7 @@ LDLIB := -l$(LIB)
export LD_LIBRARY_PATH = $(LIBDIR)
CFLAGS += -std=gnu99
#CFLAGS += -O2
CFLAGS += -O2
CFLAGS += -g
CFLAGS += -Wall
CFLAGS += -Wextra

47
2021/day11/README.txt
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@@ -299,5 +299,50 @@ After 100 steps, there have been a total of 1656 flashes.
Given the starting energy levels of the dumbo octopuses in your cavern, simulate 100 steps. How many total flashes are there after 100 steps?
Your puzzle answer was 1739.
--- Part Two ---
The first half of this puzzle is complete! It provides one gold star: *
It seems like the individual flashes aren't bright enough to navigate. However, you might have a better option: the flashes seem to be synchronizing!
In the example above, the first time all octopuses flash simultaneously is step 195:
After step 193:
5877777777
8877777777
7777777777
7777777777
7777777777
7777777777
7777777777
7777777777
7777777777
7777777777
After step 194:
6988888888
9988888888
8888888888
8888888888
8888888888
8888888888
8888888888
8888888888
8888888888
8888888888
After step 195:
0000000000
0000000000
0000000000
0000000000
0000000000
0000000000
0000000000
0000000000
0000000000
0000000000
If you can calculate the exact moments when the octopuses will all flash simultaneously, you should be able to navigate through the cavern. What is the first step during which all octopuses flash?
Your puzzle answer was 324.
Both parts of this puzzle are complete! They provide two gold stars: **

111
2021/day11/aoc-c.c
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@@ -46,6 +46,7 @@ inline static int pop()
return stack[--nstack];
}
#ifdef DEBUG
static void print_grid(int (*arr)[MAX_GRID], int step)
{
log_f(3, "step = %d\n", step);
@@ -56,8 +57,9 @@ static void print_grid(int (*arr)[MAX_GRID], int step)
log(3, "\n");
}
}
#endif
inline static int inc_cell(int l, int c)
inline static int flash_cell_maybe(int l, int c)
{
if (VALID(l, c) && ++grid[l][c] == 10) {
push(l, c);
@@ -66,57 +68,57 @@ inline static int inc_cell(int l, int c)
return 0;
}
void flash_grid(int (*arr)[MAX_GRID], int step)
{
log_f(3, "step = %d\n", step);
for (int l = 1; l <= gsize; ++l) {
for (int c = 1; c <= gsize; ++c) {
log(3, "%2d ", arr[l][c]);
}
log(3, "\n");
}
}
/* run 1 step */
static void step(int nsteps)
static int do_step()
{
int vpop;
int flash = 0;
//int flashed[MAX_GRID][MAX_GRID];
int vpop, flash = 0;
//init_grid(flashed);
/* create an empty grid */
for (int step = 1; step <= nsteps; ++step) {
/* 1) increase all energy levels */
for (int l = 0; l < gsize; ++l) {
for (int c = 0; c < gsize; ++c) {
flash += inc_cell(l, c);
}
/* 1) increase all energy levels */
for (int l = 0; l < gsize; ++l) {
for (int c = 0; c < gsize; ++c) {
flash += flash_cell_maybe(l, c);
}
/* 2) perform BFS until stack is empty */
while ((vpop = pop()) != -1) {
int pl = vpop / gsize, pc = vpop % gsize;
for (int l = -1; l <= 1; ++l)
for (int c = -1; c <= 1; ++c)
flash += inc_cell(pl + l, pc + c);
}
//print_grid(grid, 1);
/* 3) cleanup flashed cells */
for (int l = 0; l < gsize; ++l) {
for (int c = 0; c < gsize; ++c) {
if (grid[l][c] > 9)
grid[l][c] = 0;
}
}
print_grid(grid, step);
printf("step = %d flashed = %d\n", step, flash);
}
/* 2) perform BFS until stack is empty */
while ((vpop = pop()) != -1) {
int pl = vpop / gsize, pc = vpop % gsize;
for (int l = -1; l <= 1; ++l) {
for (int c = -1; c <= 1; ++c) {
flash += flash_cell_maybe(pl + l, pc + c);
}
}
}
/* 3) cleanup flashed cells */
for (int l = 0; l < gsize; ++l) {
for (int c = 0; c < gsize; ++c) {
if (grid[l][c] > 9)
grid[l][c] = 0;
}
}
return flash;
}
static s64 doit(int part)
static int part1(int nsteps)
{
int flash = 0;
for (int step = 1; step <= nsteps; ++step)
flash += do_step();
return flash;
}
static int part2()
{
int flash = 0, step;
for (step = 0; flash != 100; ++step)
flash = do_step(step);
return step;
}
static int doit(int part)
{
int l = 0, c;
ssize_t len;
@@ -127,16 +129,12 @@ static s64 doit(int part)
gsize = len - 1;
for (l = 0; l < gsize; ++l) {
buf[gsize] = 0;
log_f(10, "len = %d str = [%s]\n", grid, buf);
for (c = 0, p = buf; c < gsize; c++, p++)
grid[l][c] = *p - '0';
getline(&buf, &alloc, stdin);
}
free(buf);
print_grid(grid, 0);
step(100);
print_grid(grid, 1);
return part;
return part == 1? part1(100): part2();
}
static int usage(char *prg)
@@ -147,9 +145,7 @@ static int usage(char *prg)
int main(int ac, char **av)
{
int opt;
u32 exercise = 1, debug = 1;
s64 res;
int opt, res, part = 1, debug = 0;
while ((opt = getopt(ac, av, "d:p:")) != -1) {
switch (opt) {
@@ -157,8 +153,8 @@ int main(int ac, char **av)
debug = atoi(optarg);
break;
case 'p': /* 1 or 2 */
exercise = atoi(optarg);
if (exercise < 1 || exercise > 2)
part = atoi(optarg);
if (part < 1 || part > 2)
return usage(*av);
break;
default:
@@ -169,8 +165,7 @@ int main(int ac, char **av)
if (optind < ac)
return usage(*av);
//init_borders();
res = doit(exercise);
printf("%s : res=%lu\n", *av, res);
res = doit(part);
printf("%s : res=%d\n", *av, res);
exit (0);
}