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advent-of-code/2021/day19/aoc-c.c

598 lines
19 KiB
C

/* aoc-c.c: Advent of Code 2021, day 19 parts 1 & 2
*
* Copyright (C) 2022 Bruno Raoult ("br")
* Licensed under the GNU General Public License v3.0 or later.
* Some rights reserved. See COPYING.
*
* You should have received a copy of the GNU General Public License along with this
* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
*
* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "pool.h"
#include "debug.h"
#include "bits.h"
#include "list.h"
/*
typedef struct beacon {
int x, y, z;
struct list_head list_beacons;
} beacon_t;
typedef struct scanner {
struct list_head list_beacons;
} scanner_t;
*/
// #define SQUARE(x) ((x) * (x))
#define MAX_SCANNERS 32 /* I know, I know... */
#define MAX_BEACONS 32
#define MAX_DISTANCES ((MAX_BEACONS - 1) * MAX_BEACONS)
typedef struct vector {
int x, y, z; /* beacon coordinates */
} vector_t;
typedef struct beacon {
int x, y, z; /* beacon coordinates */
int count;
} beacon_t;
typedef struct rotmatrix {
vector_t a, b, c;
} rotmatrix_t;
typedef struct dist {
uint dist; /* square distance */
int beacon1, beacon2; /* beacons */
} dist_t;
typedef struct scanner {
int nbeacons, ndists, adjusted;
beacon_t beacons[MAX_BEACONS];
uint beacons_count[MAX_BEACONS]; /* common scanner distance count */
dist_t dists[MAX_DISTANCES]; /* sorted */
int reference[3]; /* reference beacons */
} scanner_t;
static pool_t *pool_beacon;
static scanner_t scanners[MAX_SCANNERS];
static int nscanners;
static void scanners_print_dists()
{
dist_t *cur;
log_f(1, "nscanners: %d\n", nscanners);
for (int i = 0; i < nscanners; ++i) {
log(1, "scanner %d:\n", i);
for (int j = 0; j < scanners[i].ndists; ++j) {
cur = &scanners[i].dists[j];
log(1, "\t%u : %d,%d\n", cur->dist, cur->beacon1, cur->beacon2);
}
// log(1, "zobi\n");
}
}
static void scanners_print_refs(scanner_t *s1, scanner_t *s2)
{
log_f(1, "s1:%ld s2:%ld\n", s1 - scanners, s2 - scanners);
log(1, "scanner %ld:", s1 - scanners);
for (int i = 0; i < 3; ++i) {
beacon_t *beacon = s1->beacons + s1->reference[i];
log(1, " (%d,%d,%d)", beacon->x, beacon->y, beacon->z);
}
log(1, "\nscanner %ld:", s2 - scanners);
for (int i = 0; i < 3; ++i) {
beacon_t *beacon = s2->beacons + s2->reference[i];
log(1, " (%d,%d,%d)", beacon->x, beacon->y, beacon->z);
}
log(1, "\n");
}
/*
static void scanners_print()
{
beacon_t *cur;
log_f(1, "nscanners: %d\n", nscanners);
for (int i = 0; i < nscanners; ++i) {
log(1, "scanner %d:\n\t", i);
for (int j = 0; j < scanners[i].nbeacons; ++j) {
cur = &scanners[i].beacons[j];
log(1, " %d/%d/%d", cur->x, cur->y, cur->z);
}
log(1, "\n");
}
}
*/
static void merge(array, left, mid, right)
dist_t *array;
int left, mid, right;
{
dist_t temp[right - left + 1];
int pos = 0, lpos = left, rpos = mid + 1, iter;
while(lpos <= mid && rpos <= right) {
if(array[lpos].dist < array[rpos].dist) {
temp[pos++] = array[lpos++];
}
else {
temp[pos++] = array[rpos++];
}
}
while(lpos <= mid)
temp[pos++] = array[lpos++];
while(rpos <= right)
temp[pos++] = array[rpos++];
for(iter = 0; iter < pos; iter++) {
array[iter+left] = temp[iter];
}
return;
}
static void mergesort(array, left, right)
dist_t *array;
int left, right;
{
int mid = (left + right) / 2;
if(left < right) {
mergesort(array, left, mid);
mergesort(array, mid + 1, right);
merge(array, left, mid, right);
}
}
/* Thanks to:
* http://www.euclideanspace.com/maths/algebra/matrix/transforms/examples/index.htm
*/
rotmatrix_t rotations[24] = {
{{ 1, 0, 0}, { 0, 1, 0}, { 0, 0, 1}},
{{ 0, 0, 1}, { 0, 1, 0}, {-1, 0, 0}},
{{-1, 0, 0}, { 0, 1, 0}, { 0, 0, -1}},
{{ 0, 0, -1}, { 0, 1, 0}, { 1, 0, 0}},
{{ 0, -1, 0}, { 1, 0, 0}, { 0, 0, 1}},
{{ 0, 0, 1}, { 1, 0, 0}, { 0, 1, 0}},
{{ 0, 1, 0}, { 1, 0, 0}, { 0, 0, -1}},
{{ 0, 0, -1}, { 1, 0, 0}, { 0, -1, 0}},
{{ 0, 1, 0}, {-1, 0, 0}, { 0, 0, 1}},
{{ 0, 0, 1}, {-1, 0, 0}, { 0, -1, 0}},
{{ 0, -1, 0}, {-1, 0, 0}, { 0, 0, -1}},
{{ 0, 0, -1}, {-1, 0, 0}, { 0, 1, 0}},
{{ 1, 0, 0}, { 0, 0, -1}, { 0, 1, 0}},
{{ 0, 1, 0}, { 0, 0, -1}, {-1, 0, 0}},
{{-1, 0, 0}, { 0, 0, -1}, { 0, -1, 0}},
{{ 0, -1, 0}, { 0, 0, -1}, { 1, 0, 0}},
{{ 1, 0, 0}, { 0, -1, 0}, { 0, 0, -1}},
{{ 0, 0, -1}, { 0, -1, 0}, {-1, 0, 0}},
{{-1, 0, 0}, { 0, -1, 0}, { 0, 0, 1}},
{{ 0, 0, 1}, { 0, -1, 0}, { 1, 0, 0}},
{{ 1, 0, 0}, { 0, 0, 1}, { 0, -1, 0}},
{{ 0, -1, 0}, { 0, 0, 1}, {-1, 0, 0}},
{{-1, 0, 0}, { 0, 0, 1}, { 0, 1, 0}},
{{ 0, 1, 0}, { 0, 0, 1}, { 1, 0, 0}},
};
#define NROTATIONS (sizeof(rotations) / sizeof(*rotations))
/* beacon_rotate: rotate beacon "in" with "nrot"th rotations matrix
*/
static beacon_t *beacon_rotate(const beacon_t *in, beacon_t *res, rotmatrix_t *rot)
{
res->x = in->x * rot->a.x + in->y * rot->a.y + in->z * rot->a.z;
res->y = in->x * rot->b.x + in->y * rot->b.y + in->z * rot->b.z;
res->z = in->x * rot->c.x + in->y * rot->c.y + in->z * rot->c.z;
return res;
}
/* beacon_diff: calculate difference between 2 beacons
*/
static beacon_t *beacon_diff(const beacon_t *b1, beacon_t *b2, beacon_t *res)
{
res->x = b1->x - b2->x;
res->y = b1->y - b2->y;
res->z = b1->z - b2->z;
return res;
}
/* using scanner's reference points, find the correct rotation and translation
*/
static int adjust_scanner(scanner_t *ref, scanner_t *s)
{
beacon_t *beacon_ref[3], *beacon[3];
//log_f(1, "sizeof(rotations)=%lu\n", NROTATIONS);
for (uint i = 0; i < 3; ++i) {
beacon_ref[i] = ref->beacons + ref->reference[i];
beacon[i] = s->beacons + s->reference[i];
}
for (uint i = 0; i < NROTATIONS; ++i) {
beacon_t rot[3], diff[3];
//int match = 1;
/* rotate the first beacon and translate to match ref's (x, y, z)
*/
for (int bref = 0; bref < 3; ++bref) {
beacon_rotate(beacon[bref], &rot[bref], rotations + i);
beacon_diff(beacon_ref[bref], &rot[bref], &diff[bref]);
log(2, "ref %d diff=(%d,%d,%d)\n", bref, diff[bref].x, diff[bref].y,
diff[bref].z);
/* check that rotation/translation works for the 3 reference points
*/
if (bref > 0 && (diff[bref].x != diff[0].x ||
diff[bref].y != diff[0].y ||
diff[bref].z != diff[0].z)) {
log(2, "skipping this translation\n");
goto next_rot;
}
}
log(2, "Got it: scanner %lu is (%d,%d,%d) from reference\n",
s - scanners, diff[0].x, diff[0].y, diff[0].z);
/* adjust all beacons */
for (int b = 0; b < s->nbeacons; ++ b) {
beacon_rotate(s->beacons + b, rot, rotations + i);
s->beacons[b] = *rot;
s->beacons[b].x += (*diff).x;
s->beacons[b].y += (*diff).y;
s->beacons[b].z += (*diff).z;
log(2, "translated beacon: (%d,%d,%d)\n", s->beacons[b].x,
s->beacons[b].y, s->beacons[b].z);
//beacon_diff(beacon_ref[bref], &rot[bref], &diff[bref]);
}
break;
next_rot:
log(2, "\n");
}
return 1;
}
static int count_common_distances(scanner_t *s1, scanner_t *s2)
{
dist_t *d1 = s1->dists, *d2 = s2->dists;
int cur1 = 0, cur2 = 0, i;
int ref_triangle = 0;
uint count = 0;
//beacon_t *beacon1 = s1->beacons, *beacon2 = s2->beacons;
/* initialize s1 and s2 beacons count
*/
for (i = 0; i < MAX_BEACONS; ++i) {
s1->beacons_count[i] = 0;
s2->beacons_count[i] = 0;
}
log_f(1, "(%ld, %ld): \n", s1 - scanners, s2 - scanners);
/* We need to find common references A, B, C such as:
*
* d1
* A------------------B
* \ /
* d2\ +----------/
* \ / (d3)
* C
* To do so, we find common d1 and d2 such as both have
* a common A point.
*/
while (cur1 < s1->ndists && cur2 < s2->ndists) {
if (d1[cur1].dist == d2[cur2].dist) {
log(1, " %u: (%d,%d)= %d-%d %d-%d triangle=%d\n",
d1[cur1].dist, cur1, cur2,
d1[cur1].beacon1, d1[cur1].beacon2,
d2[cur2].beacon1, d2[cur2].beacon2,
ref_triangle);
if (ref_triangle == 0) {
/* both s1 s2 refs may be reversed */
s1->reference[0] = d1[cur1].beacon1;
s1->reference[1] = d1[cur1].beacon2;
s2->reference[0] = d2[cur2].beacon1;
s2->reference[1] = d2[cur2].beacon2;
ref_triangle = 2;
log(2, "\ts1_ref=%d,%d,%d s2_ref=%d,%d,%d\n",
s1->reference[0], s1->reference[1], s1->reference[2],
s2->reference[0], s2->reference[1], s2->reference[2]);
} else if (ref_triangle == 2) {
int beacon1 , beacon2;
/* we need to adjust references for the two pairs of
* 2 beacons having same distance, for scanner 1.
*/
beacon1 = d1[cur1].beacon1;
beacon2 = d1[cur1].beacon2;
log(2, "\ts1 bea1=%d bea2=%d\n\t ref0=%d ref1=%d\n",
beacon1, beacon2, s1->reference[0], s1->reference[1]);
if (beacon1 == s1->reference[0]) {
/* ref0----------ref1
* ref0----------ref2
*/
s1->reference[2] = beacon2;
ref_triangle++;
} else if (beacon1 == s1->reference[1]) {
/* ref1----------ref0
* ref0----------ref2
* first & second reference beacons must be reversed,
* second is ok
*/
int tmp = s1->reference[0];
s1->reference[0] = s1->reference[1];
s1->reference[1] = tmp;
s1->reference[2] = beacon2;
ref_triangle++;
} else if (beacon2 == s1->reference[0]) {
/* ref0----------ref1
* ref2----------ref0
*/
s1->reference[2] = beacon1;
ref_triangle++;
} else if (beacon2 == s1->reference[1]) {
/* ref1----------ref0
* ref2----------ref0
*/
int tmp = s1->reference[0];
s1->reference[0] = s1->reference[1];
s1->reference[1] = tmp;
s1->reference[2] = beacon1;
ref_triangle++;
}
/* we do the same for second scanner */
beacon1 = d2[cur2].beacon1;
beacon2 = d2[cur2].beacon2;
if (beacon1 == s2->reference[0]) {
/* ref0----------ref1
* ref0----------ref2
*/
s2->reference[2] = beacon2;
ref_triangle++;
} else if (beacon1 == s2->reference[1]) {
/* ref1----------ref0
* ref0----------ref2
* first & second reference beacons must be reversed,
* second is ok
*/
int tmp = s2->reference[0];
s2->reference[0] = s2->reference[1];
s2->reference[1] = tmp;
s2->reference[2] = beacon2;
ref_triangle++;
} else if (beacon2 == s2->reference[0]) {
/* ref0----------ref1
* ref2----------ref0
*/
s2->reference[2] = beacon1;
ref_triangle++;
} else if (beacon2 == s2->reference[1]) {
/* ref1----------ref0
* ref2----------ref0
*/
int tmp = s2->reference[0];
s2->reference[0] = s2->reference[1];
s2->reference[1] = tmp;
s2->reference[2] = beacon1;
ref_triangle++;
}
log(2, "\ttriangle=%d s1_ref=%d,%d,%d s2_ref=%d,%d,%d\n",
ref_triangle,
s1->reference[0], s1->reference[1], s1->reference[2],
s2->reference[0], s2->reference[1], s2->reference[2]);
}
/*
if (ref_triangle == 3) {
if (d1[cur1].beacon1 == s1->reference[0] ||
d1[cur1].beacon1 == s1->reference[1]) {
s1->reference[2] = d2[cur1].beacon2;
ref_triangle++;
} else if (d1[cur1].beacon2 == s1->reference[0] ||
d1[cur1].beacon2 == s1->reference[1]) {
s1->reference[2] = d1[cur1].beacon1;
ref_triangle++;
}
}
*/
++s1->beacons_count[d1[cur1].beacon1];
++s1->beacons_count[d1[cur1].beacon2];
++s2->beacons_count[d2[cur2].beacon1];
++s2->beacons_count[d2[cur2].beacon2];
++count;
++cur1;
++cur2;
}
else if (d1[cur1].dist < d2[cur2].dist) {
++cur1;
} else {
++cur2;
}
}
log_i(1, "\n");
return count;
}
static void calc_square_distances()
{
scanner_t *scanner;
beacon_t *b1, *b2;
uint dist;
log_f(1, "nscanners: %d\n", nscanners);
for (int i = 0; i < nscanners; ++i) {
scanner = scanners + i;
for (int j = 0; j < scanner->nbeacons; ++j) {
b1 = scanner->beacons + j;
for (int k = j + 1; k < scanner->nbeacons; ++k) {
scanner->dists[scanner->ndists].beacon1 = j;
scanner->dists[scanner->ndists].beacon2 = k;
b2 = scanner->beacons + k;
dist = (b1->x - b2->x) * (b1->x - b2->x) +
(b1->y - b2->y) * (b1->y - b2->y) +
(b1->z - b2->z) * (b1->z - b2->z);
scanner->dists[scanner->ndists].dist = dist;
scanner->ndists++;
log(5, "\tdist(%d/%d) = %u\n",
j, k,
dist);
}
}
//scanners_print_dists();
mergesort(scanner->dists, 0, scanner->ndists - 1);
}
scanners_print_dists();
//log(1, "\n");
}
/* match all scanners
*/
static void match_scanners()
{
int finished = 0;
scanners[0].adjusted = 1;
while (!finished) {
finished = 1;
for (int i = 0; i < nscanners - 1; ++i) {
if (!scanners[i].adjusted) /* skip un-translated scanners */
continue;
for (int j = 0; j < nscanners; ++j) {
if (i == j || scanners[j].adjusted) /* already translated */
continue;
int count = count_common_distances(scanners + i, scanners + j);
log(1, "common(%d, %d) = %d\n", i, j, count);
if (count >= 66) {
/*
beacon_t *beacon;
for (int k = 0; k < scanners[i].nbeacons; ++k) {
beacon = scanners[i].beacons + k;
//if (beacon->count >= 11)
log(1, "s1(%d, %d, %d): %d\n", beacon->x, beacon->y,
beacon->z, scanners[i].beacons_count[k]);
}
for (int k = 0; k < scanners[j].nbeacons; ++k) {
beacon = scanners[j].beacons + k;
//if (beacon->count >= 11)
log(1, "s2(%d, %d, %d): %d\n", beacon->x, beacon->y,
beacon->z, scanners[j].beacons_count[k]);
}
*/
adjust_scanner(scanners + i, scanners + j);
scanners[j].adjusted = 1;
finished = 0;
//scanners_print_refs(scanners + i, scanners + j);
}
}
}
}
}
/* read input
*/
static int read_lines()
{
size_t alloc = 0;
ssize_t buflen;
char *buf = NULL;
beacon_t *beacon;
scanner_t *scanner = NULL;
//int nbeacon = 0;
while ((buflen = getline(&buf, &alloc, stdin)) > 0) {
//buf[--buflen] = 0;
switch (buf[1]) {
case '-':
scanner = scanners + nscanners;
log_f(2, "[%c] nscanners = %d %p/%p\n", *buf, nscanners,
scanner, scanners);
//INIT_LIST_HEAD(&scanner->list_beacons);
nscanners++;
scanner->nbeacons = 0;
break;
case '\0':
log_f(2, "NULL line\n");
break;
default:
//log_f(2, "[%c] beacon = %d\n", *buf, nscanners);
//beacon = pool_get(pool_beacon);
//list_add_tail(&beacon->list_beacons, &scanner->list_beacons);
beacon = &scanner->beacons[scanner->nbeacons];
sscanf(buf, "%d,%d,%d", &beacon->x, &beacon->y, &beacon->z);
//log_f(2, "beacon %d = %d/%d/%d\n", nbeacon, beacon->x, beacon->y, beacon->z);
scanner->nbeacons++;
}
}
free(buf);
calc_square_distances();
return nscanners;
}
static s64 part1()
{
return 1;
}
static s64 part2()
{
return 2;
}
static int usage(char *prg)
{
fprintf(stderr, "Usage: %s [-d debug_level] [-p part]\n", prg);
return 1;
}
int main(int ac, char **av)
{
int opt, part = 1;
while ((opt = getopt(ac, av, "d:p:")) != -1) {
switch (opt) {
case 'd':
debug_level_set(atoi(optarg));
break;
case 'p': /* 1 or 2 */
part = atoi(optarg);
if (part < 1 || part > 2)
return usage(*av);
break;
default:
return usage(*av);
}
}
if (optind < ac)
return usage(*av);
if (!(pool_beacon = pool_create("beacons", 1024, sizeof(beacon_t)))) {
log(1, "pool create error, errno=%d\n", errno);
exit(1);
}
read_lines();
match_scanners();
log_f(1, "sizeof(rotations)=%lu, sizeof2=%lu sizeof2=%lu\n", sizeof(rotations),
sizeof(*rotations), sizeof(rotations) / sizeof(*rotations));
printf("%s : res=%ld\n", *av, part == 1? part1(): part2());
pool_destroy(pool_beacon);
exit(0);
}