148 lines
3.2 KiB
C
148 lines
3.2 KiB
C
/* aoc-c: Advent2021 game, day 6 parts 1 & 2
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*
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* Copyright (C) 2021 Bruno Raoult ("br")
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* Licensed under the GNU General Public License v3.0 or later.
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* Some rights reserved. See COPYING.
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*
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* You should have received a copy of the GNU General Public License along with this
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* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
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*
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* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <malloc.h>
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#include "debug.h"
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#include "bits.h"
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static int ncrabs, crab_grow, crab_alloc, crab_max;
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typedef struct crab {
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int pos;
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int ncrabs;
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} crab_t;
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crab_t *crabs = NULL;
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//#ifdef DEBUG
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static void print_crab()
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{
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int i = 0;
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printf("crabs=%d max=%d\n", ncrabs, crab_max);
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for (i = 0; i < ncrabs; ++i)
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printf("%s%d/%d", i? ", ": "", crabs[i].pos, crabs[i].ncrabs);
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printf("\n");
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}
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//#endif
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static crab_t *grow_crabs()
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{
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//static int crab_max = 0;
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int old = crab_alloc;
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crab_alloc += crab_grow;
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crabs = realloc(crabs, crab_alloc * sizeof (*crabs));
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for (int i = old; i < crab_alloc; ++i) {
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crabs[i].pos = -1;
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crabs[i].ncrabs = 0;
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}
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return crabs;
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}
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static int add_crab(int crab)
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{
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int i;
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if (crab > crab_max)
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crab_max = crab;
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if (ncrabs == crab_alloc) /* conservative grow */
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grow_crabs();
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for (i = 0; i < ncrabs; ++i) {
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if (crabs[i].pos == crab) {
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crabs[i].ncrabs++;
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return i;
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}
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}
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crabs[i].pos = crab;
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crabs[i].ncrabs = 1;
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ncrabs++;
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return i;
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}
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static u64 read_crab()
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{
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char *buf, *token;
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size_t alloc = 0;
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ssize_t length;
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if ((length = getline(&buf, &alloc, stdin)) < 0)
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return -1;
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crab_grow = length / 2;
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token = strtok(buf, ",\n");
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while (token) {
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add_crab(atoi(token));
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token = strtok(NULL, ",\n");
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}
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free(buf);
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return ncrabs;
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}
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static int doit(int part)
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{
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int try, best_dist = 0, best_fuel = crab_max * crab_max;
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if (part == 1) {
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for (try = 0; try < crab_max; ++try) {
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int fuel = 0;
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for (int crab = 0; crab < ncrabs; ++crab)
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fuel += abs(crabs[crab].pos - try) * crabs[crab].ncrabs;
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if (fuel < best_fuel) {
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best_dist = try;
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best_fuel = fuel;
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}
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}
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}
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return best_fuel;
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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(int ac, char **av)
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{
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int opt;
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u32 exercise = 1;
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int res;
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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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exercise = atoi(optarg);
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if (exercise < 1 || exercise > 2)
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return usage(*av);
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break;
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default:
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return usage(*av);
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}
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}
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if (optind < ac)
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return usage(*av);
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read_crab();
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res = doit(exercise);
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printf ("%s : res=%d\n", *av, res);
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exit (0);
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}
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