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advent-of-code/2022/day15/aoc-c.c
Bruno Raoult 0a3b404c4c 2022 day 15: part 2 (C)
2023-03-25 13:31:40 +01:00

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/* aoc-c.c: Advent of Code 2022, day 15
*
* 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 <string.h>
#include <ctype.h>
#include <limits.h>
#include <string.h>
#include "br.h"
#include "list.h"
#include "pool.h"
#include "hashtable.h"
#include "pjwhash-inline.h"
#include "debug.h"
#include "aoc.h"
static pool_t *pool_segment, *pool_row;
#define HBITS 20 /* 20 bits: 1,048,576 buckets */
static DEFINE_HASHTABLE(hasht_rows, HBITS);
/**
* struct map - full map
* @xmin, @xmax: most left/right x-coordinates.
* @ymin, @ymax: most top/bottom y-coordinates.
* @hash: rows hash table
*/
struct map {
int xmin, xmax, ymin, ymax;
struct hlist_head *hash;
} map = {
//INT_MAX, INT_MIN, INT_MAX, INT_MIN, hasht_rows
INT_MIN, INT_MAX, INT_MIN, INT_MAX, hasht_rows
};
/**
* struct row - row description
* @row: row number.
* @segments: segments list.
* @hlist: htable bucket list.
*/
struct row {
int row;
int beacons[64];
int nbeacons;
struct list_head segments;
struct hlist_node hlist;
};
/**
* struct segment - The main segment structure
* @row: the row number
* @start, @end: segment start and end
* @list: sorted row's segments list
*
* If a row contains 2 segments 1-3 and 7-8, it would be represented as:
* +----------+ +----------+
* | start: 1 |<------>| start: 7 |
* | end: 3 | | end: 8 |
* +----------+ +----------+
*
* This implies adding a segment must manage merging. For example, adding
* segment 2-4 above would change the first segment to 1-4, or adding 0-9
* should change the first segment to 0-9 and remove the second one.
*/
struct segment {
int row;
int start, end;
struct list_head list;
};
static struct row *find_row(struct hlist_head *head, int row)
{
struct row *cur;
hlist_for_each_entry(cur, head, hlist)
if (cur->row == row)
return cur;
return NULL;
}
static void print_segments()
{
struct row *prow;
struct segment *s;
//log_f(1, "xmin=%d xmax=%d\n", map.xmin, map.xmax);
if (! testmode())
return;
for (int y = -3; y <= 22; ++y) {
if ((prow = find_row(&map.hash[hash_32(y, HBITS)], y))) {
log(1, "%2d ", y);
log(5, "prow(%d->%d)=%p\n", y, hash_32(y, HBITS), prow);
int count = 0;
list_for_each_entry(s, &prow->segments, list) {
log(1, "%s (%d,%d)", count? " -> ":"", s->start, s->end);
}
log(1, "\n");
}
}
}
static void print_map() /* for test mode only */
{
struct row *prow;
struct segment *s;
//log_f(1, "xmin=%d xmax=%d\n", map.xmin, map.xmax);
if (! testmode())
return;
log(1, " - 1 1 2 2 3\n");
log(1, " 5 0 5 0 5 0 5 0\n");
for (int y = -3; y <= 22; ++y) {
if ((prow = find_row(&map.hash[hash_32(y, HBITS)], y))) {
log(1, "%2d ", y);
log(5, "prow(%d->%d)=%p\n", y, hash_32(y, HBITS), prow);
int x = -6;
list_for_each_entry(s, &prow->segments, list) {
//log_f(1, "segment start=%d end=%d\n", s->start, s->end);
for (; x <= 30 && x < s->start; ++x) {
log(1, ".");
}
for (; x <= 30 && x <= s->end; ++x) {
log(1, "#");
}
}
for (; x <= 30; ++x) {
log(1, ".");
}
log(1, "\n");
}
}
}
static struct segment *get_segment(int row, int x1, int x2)
{
struct segment *new = pool_get(pool_segment);
log_f(5, "alloc segment (%d,%d) on row (%d)\n", x1, x2, row);
new->row=row;
new->start=x1;
new->end=x2;
INIT_LIST_HEAD(&new->list);
return new;
}
static int merge_segment(struct row *prow, int start, int end)
{
struct segment *seg, *new;
struct list_head *cur, *tmp;
int l;
l = debug_level_get();
//if (prow->row != 9)
l++;
log_f(l, "merging segment (%d,%d) on row (%d)\n", start, end, prow->row);
new = get_segment(prow->row, start, end);
if (list_empty(&prow->segments)) {
log_f(l, " first segment\n");
list_add(&new->list, &prow->segments);
goto end;
}
list_for_each_safe(cur, tmp, &prow->segments) {
seg = list_entry(cur, struct segment, list);
log_f(l, "compare to (start=%d end=%d)\n", seg->start, seg->end);
/* 1) check for disjoint segments */
if (start > seg->end + 1) {
log_f(l, " skipping (%d,%d)\n", seg->start, seg->end);
continue;
}
if (end < seg->start - 1) {
log_f(l, " adding before (%d,%d)\n", seg->start, seg->end);
list_add_tail(&new->list, &seg->list);
goto end;
}
/* new is inside cur: do nothing */
if (start >= seg->start && end <= seg->end) {
log_f(l, " overlap IN, do nothing\n");
pool_add(pool_segment, new);
goto end;
}
/* cur inside new: remove cur */
if (start <= seg->start && end >= seg->end) {
log_f(l, " overlap OUT, remove current\n");
// TODO: avoid this
list_del(cur);
pool_add(pool_segment, seg);
continue;
}
/* 2) adjacent block */
if (start >= seg->start && start <= seg->end + 1) {
log_f(l, " setting new start to %d\n", seg->start);
new->start = seg->start;
list_del(cur);
pool_add(pool_segment, seg);
continue;
}
if (end == seg->start - 1) {
seg->start = start;
pool_add(pool_segment, new);
goto end;
}
/* we know here there is at least one overlap or contiguous */
log_f(l, " could merge new=(%d,%d) with cur=(%d,%d)\n",
start, end, seg->start, seg->end);
/* exactly one overlap */
log_f(3, " exactly one overlap\n");
if (start >= seg->start) {
log_f(l, " overlap left new=(%d,%d)\n", new->start, new->end);
new->start = seg->start;
}
if (end >= seg->end){
log_f(l, " overlap right: delete cur\n");
list_del(cur);
pool_add(pool_segment, seg);
continue;
}
/* we stop here */
log_f(l, " stop here\n");
new->end = seg->end;
list_add_tail(&new->list, cur);
list_del(cur);
pool_add(pool_segment, seg);
goto end;
}
log_f(l, " adding at end of list\n");
list_add_tail(&new->list, &prow->segments);
end:
//print_segments();
return 10;
}
static void add_beacon(int bx, int by)
{
uint hash = by, bucket = hash_32(hash, HBITS);
struct row *prow = find_row(&map.hash[bucket], hash);
if (!prow) {
puts("fuck)");
exit(1);
}
for (int i = 0; i < prow->nbeacons; ++i) {
if (prow->beacons[i] == bx)
return;
}
prow->beacons[prow->nbeacons++] = bx;
}
static int add_segment(int row, int center, int half)
{
int x1, x2;
uint hash = row, bucket = hash_32(hash, HBITS);
struct row *prow = find_row(&map.hash[bucket], hash);
x1 = max(center - half, map.xmin);
x2 = min(center + half, map.xmax);
if (x1 != center - half || x2 != center + half)
log(1, "adjust x: min:%d->%d max:%d->%d\n",
center - half, x1, center + half, x2);
log_f(3, "adding segment (%d,%d) on row (%d) - bucket(%u) = %u prow=%p\n",
x1, x2, row, hash, bucket, prow);
/*
* if (row < map.ymin) {
* log(5, "new ymin=%d->%d\n", map.ymin, row);
* map.ymin = row;
* }
* if (row > map.ymax) {
* log(5, "new ymax=%d->%d\n", map.ymax, row);
* map.ymax = row;
* }
* if (x1 < map.xmin) {
* log(5, "new xmin=%d->%d\n", map.xmin, x1);
* map.xmin = x1;
* }
* if (x2 > map.xmax) {
* log(5, "new xmax=%d->%d\n", map.xmax, x2);
* map.xmax = x2;
* }
*/
log(3, "map borders: xmin=%d xmax=%d ymin=%d ymax=%d\n",
map.xmin, map.xmax, map.ymin, map.ymax);
if (!prow) {
prow = pool_get(pool_row);
prow->row = row;
prow->nbeacons = 0;
INIT_HLIST_NODE(&prow->hlist);
INIT_LIST_HEAD(&prow->segments);
hlist_add_head(&prow->hlist, &map.hash[bucket]);
}
merge_segment(prow, x1, x2);
return 1;
}
static int add_segments(int sx, int sy, int bx, int by)
{
int manhattan = abs(bx - sx) + abs(by - sy);
int ymin = max(sy - manhattan, map.ymin);
int ymax = min(sy + manhattan, map.ymax);
log_f(2, "sensor4=(%d, %d) beacon=(%d, %d) - ", sx, sy, bx, by);
log(2, "manhattan=%u ymin=%d ymax=%d\n", manhattan, ymin, ymax);
//add_segment(sy, sx, manhattan);
for (int y = ymin; y <= ymax; ++y) {
int half = manhattan - abs(y - sy);
add_segment(y, sx, half);
if (y == by)
add_beacon(bx, by);
//add_segment(y, sx, half);
}
//for (int dy = 1, half = manhattan - 1; dy <= manhattan; ++dy, half--) {
// add_segment(sy - dy, sx, half);
// add_segment(sy + dy, sx, half);
//}
//add_beacon(bx, by);
return 1;
}
static inline int parse(int *sx, int *sy, int *bx, int *by)
{
int ret = scanf("%*[^-0-9]%d%*[^-0-9]%d%*[^-0-9]%d%*[^-0-9]%d",
sx, sy, bx, by);
return ret;
}
static ulong part1()
{
ulong res = 0;
int row = testmode() ? 10: 2000000;
uint bucket = hash_32(row, HBITS);
int sx, sy, bx, by;
map.ymin = row - 1;
map.ymax = row + 1;
while (parse(&sx, &sy, &bx, &by) > 0) {
int manhattan = abs(bx - sx) + abs(by - sy);
add_segments(sx, sy, bx, by);
log(3, "m=%d : ", manhattan);
}
struct row *prow = find_row(&map.hash[bucket], row);
if (prow) {
struct segment *cur;
print_map();
list_for_each_entry(cur, &prow->segments, list) {
printf("counting segment (%d,%d) = %d nbeac=%d\n", cur->start, cur->end,
cur->end - cur->start + 1, prow->nbeacons);
res += cur->end - cur->start + 1;
}
res -= prow->nbeacons;
}
return res;
}
static ulong part2()
{
ulong res = 0;
int sx, sy, bx, by;
map.xmin = map.ymin = 0;
map.xmax = map.ymax = testmode()? 20: 4000000;
while ((parse(&sx, &sy, &bx, &by)) > 0) {
int manhattan = abs(bx - sx) + abs(by - sy);
add_segments(sx, sy, bx, by);
log(3, "m=%d : ", manhattan);
}
for (int row = map.ymin; row <= map.ymax; ++row) {
uint bucket = hash_32(row, HBITS);
struct row *prow = find_row(&map.hash[bucket], row);
if (!prow) {
printf("fuck 1: prow(%d)=NULL\n", row);
exit(1);
}
struct segment *cur;
if (list_empty(&prow->segments)) {
puts("fuck 2\n");
continue;
}
cur = list_first_entry(&prow->segments, struct segment, list);
if (cur->end != map.xmax) {
res = ((u64)cur->end + 1UL) * 4000000UL + (u64)row;
break;
}
}
return res;
}
int main(int ac, char **av)
{
int part = parseargs(ac, av);
pool_row = pool_create("rows", 8192, sizeof(struct row));
pool_segment = pool_create("segments", 8192, sizeof(struct segment));
printf("%s: res=%lu\n", *av, part == 1? part1(): part2());
pool_destroy(pool_row);
pool_destroy(pool_segment);
exit(0);
}
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