175 lines
3.8 KiB
C
175 lines
3.8 KiB
C
/* ex1-c: Advent2020, day 24/part 1
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "bits.h"
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#include "pool.h"
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#include "debug.h"
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#include "hashtable.h"
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#include "debug.h"
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/* In day 24 tasks, we do not care the order of tiles, as we regenerate
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* a new list after each process.
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* So we will rely on a hashtable, which will allow to quickly find a
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* given point.
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*/
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typedef union coord {
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u64 val;
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struct {
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s32 x, y;
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};
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} coord_t;
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typedef struct point {
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coord_t pos;
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struct hlist_node coll; /* entry in hash table */
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struct list_head all;
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} point_t;
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#define HBITS 12 /* in bits: 12 bits = 4096 */
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#define HSIZE (1 << HBITS)
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DEFINE_HASHTABLE(hash1, HBITS);
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DEFINE_HASHTABLE(hash2, HBITS);
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struct hlist_head *cur = hash1, *next = hash2;
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pool_t *pt_pool;
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static __always_inline u32 hash(coord_t p)
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{
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return hash_64(p.val, HBITS);
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}
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static point_t *find_point(struct hlist_head *head, coord_t p)
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{
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point_t *point;
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hlist_for_each_entry(point, head, coll) {
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if (point->pos.val == p.val)
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return point;
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}
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return NULL;
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}
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static point_t *add_point(struct hlist_head *p, coord_t pos)
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{
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point_t *new;
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u32 h;
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h = hash(pos);
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if (!(new = find_point(p + h, pos))) {
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new = pool_get(pt_pool);
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new->pos.val = pos.val;
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hlist_add_head(&new->coll, p + h);
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}
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return new;
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}
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static point_t *flip_point(struct hlist_head *p, coord_t pos)
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{
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point_t *new;
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u32 h;
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log_f(3, "val=%lu x=%d y=%d ", pos.val, pos.x, pos.y);
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h = hash(pos);
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log(3, "hash=%d ", h);
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if ((new = find_point(p + h, pos))) {
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log(3, "removing tile\n");
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hlist_del(&new->coll);
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pool_add(pt_pool, new);
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new = NULL;
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} else {
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log(3, "adding tile\n");
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new = pool_get(pt_pool);
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new->pos.val = pos.val;
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hlist_add_head(&new->coll, p + h);
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}
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return new;
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}
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static int count_points(struct hlist_head *h)
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{
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point_t *cur;
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int res = 0;
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for (int bkt = 0; bkt < HSIZE; ++bkt) {
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hlist_for_each_entry(cur, &h[bkt], coll) {
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res++;
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}
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}
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return res;
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}
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static void parse()
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{
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size_t alloc;
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ssize_t len;
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char *buf = NULL;
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while ((len = getline(&buf, &alloc, stdin)) > 0) {
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buf[len - 1] = 0;
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coord_t p = { .val = 0 };
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puts(buf);
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char *c = buf;
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while (*c) {
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switch (*c) {
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case 'e':
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++p.x;
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break;
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case 'w':
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--p.x;
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break;
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case 's':
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--p.y;
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++c;
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break;
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case 'n':
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++p.y;
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++c;
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}
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if (*c == 'e')
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++p.x;
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else if (*c == 'w')
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--p.x;
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c++;
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//printf("pos=%ld x=%d y=%d\n", c - buf, p.x, p.y);
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}
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flip_point(cur, p);
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}
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}
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static int usage(char *prg)
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{
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fprintf(stderr, "Usage: %s [-d debug_level] [-p part]\n", prg);
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return 1;
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}
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int main(ac, av)
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int ac;
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char **av;
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{
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int opt, part = 1;
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ulong res = 0;
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while ((opt = getopt(ac, av, "d:p:")) != -1) {
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switch (opt) {
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case 'd':
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debug_level_set(atoi(optarg));
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break;
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case 'p': /* 1 or 2 */
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part = atoi(optarg);
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if (part < 1 || part > 2)
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default:
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return usage(*av);
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}
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}
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pt_pool = pool_create("pool_points", 256, sizeof(point_t));
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parse();
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printf("count=%d\n", count_points(cur));
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printf("%s : res=%lu\n", *av, res);
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exit (0);
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}
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