day 23: early code for bitboard approach.
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379
2021/day23/aoc-c.c
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379
2021/day23/aoc-c.c
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/* aoc-c.c: Advent of Code 2021, day 23 parts 1 & 2
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*
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* Copyright (C) 2022 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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/* Warning: Work in progress. Should not work before I spend a lot of time
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* on it, the original "bitboard" approach for moves generation is pretty
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* difficult to program/debug
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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 <errno.h>
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#include "pool.h"
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#include "debug.h"
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#include "bits.h"
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#include "list.h"
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typedef enum {
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A = 0,
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B,
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C,
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D
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} amphipod_t;
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static const u64 cost[] = {
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1, 10, 100, 1000
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};
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/* bitboards usage:
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*
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*
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* #############
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* #abcdefghijk#
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* ###l#m#n#o###
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* #p#q#r#s#
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* #########
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*
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* bit 63: a
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* bit 62: b
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* bit 61: c
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* ...
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* bit 59: e
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* ...
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* bit 57: g
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* ...
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* bit 55: i
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* ...
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* bit 53: k
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* ...
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* bit 61 - 16 = 45: l
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* bit 59 - 16 = 43: m
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* ...
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* bit 53 - 16 = 39: o
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* ...
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* bit 61 - 32 = 29: p
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* ...
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* bit 55 - 32 = 23: s
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*
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* move up is current << 16
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* move left is current << 1
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* move right is current >> 1
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*
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* forbidden mask:
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* abcdefghijk l m n o p q r s
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* ...........1111111.1.1.1.111111111.1.1.1.11111111111111111111111
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* 0000000000011111110101010111111111010101011111111111111111111111
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*
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* allowed mask:
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* abcdefghijk l m n o p q r s
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* 1111111111100000001010101000000000101010100000000000000000000000
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* ...........1111111.1.1.1.111111111.1.1.1.11111111111111111111111
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* 0000000000011111110101010111111111010101011111111111111111111111
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*/
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#define FORBIDDEN 0x1FD57FD57FFFFFUL
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#define ALLOWED (~FORBIDDEN)
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typedef struct pos {
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u64 amp[4]; /* bitboards */
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int moves;
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u64 cost;
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u64 occupied;
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u64 available; /* ALLOWED & ~occupied */
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struct list_head list_pos;
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} pos_t;
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pool_t *pool_pos;
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pos_t *pos_zero;
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static inline u64 get_occupancy(pos_t *pos)
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{
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return pos->amp[0] | pos->amp[1] | pos->amp[2] | pos->amp[3];
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}
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/* here we allow mask to be in forbidden places
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*/
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static void mask_print(u64 bits)
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{
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//log_f(1, "A=%lx %lu\n", pos->amp[A], pos->amp[A]);
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//log(1, " B=%lx %lu\n", pos->amp[B], pos->amp[B]);
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//log(1, " C=%lx %lu\n", pos->amp[C], pos->amp[C]);
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//log(1, " D=%lx %lu\n", pos->amp[D], pos->amp[D]);
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u64 tmp;
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int count;
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log(4, "%lu: popcount=%d ", bits, popcount64(bits));
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bit_for_each64_2(count, tmp, bits) {
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log(4, " %d", count);
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}
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log(4, "\n");
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log(1, "#############\n#");
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for (int i = 63; i > 21; --i) {
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u64 mask = 1UL << i;
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//log(1, "bit = %d A=%d B=%d C=%d D=%d\n");
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if (bits & mask)
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printf("X");
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else if (FORBIDDEN & mask)
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printf("#");
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else
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printf(".");
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if (i == 52) { /* hallway line */
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printf("\n");
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i -= 3;
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} else if (i == (52 - 16)) { /* rooms top line */
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printf("\n ");
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i -= 5;
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} else if (i == (52 - 32)) { /* rooms bottom line */
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printf("\n ");
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i -= 5;
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}
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}
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printf("\n #########\n");
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}
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static void burrow_print(pos_t *pos)
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{
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log_f(4, "A=%lx %lu\n", pos->amp[A], pos->amp[A]);
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log(4, " B=%lx %lu\n", pos->amp[B], pos->amp[B]);
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log(4, " C=%lx %lu\n", pos->amp[C], pos->amp[C]);
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log(4, " D=%lx %lu\n", pos->amp[D], pos->amp[D]);
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for (int i = 0; i < 4; ++i) {
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u64 tmp;
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int count;
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log(4, "%c: popcount=%d ", i + 'A', popcount64(pos->amp[i]));
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bit_for_each64_2(count, tmp, pos->amp[i]) {
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log(4, " %d", count);
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}
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log(4, "\n");
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}
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log(1, "#############\n#");
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for (int i = 63; i > 21; --i) {
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u64 mask = 1UL << i;
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if (FORBIDDEN & mask)
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printf("#");
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else {
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//log(1, "bit = %d A=%d B=%d C=%d D=%d\n");
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if (pos->amp[A] & mask)
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printf("A");
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else if (pos->amp[B] & mask)
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printf("B");
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else if (pos->amp[C] & mask)
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printf("C");
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else if (pos->amp[D] & mask)
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printf("D");
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else
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printf(".");
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}
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if (i == 52) { /* hallway line */
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printf("\n");
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i -= 3;
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} else if (i == (52 - 16)) { /* rooms top line */
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printf("\n ");
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i -= 5;
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} else if (i == (52 - 32)) { /* rooms bottom line */
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printf("\n ");
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i -= 5;
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}
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}
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printf("\n #########\n");
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}
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/* get a position from memory pool
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*/
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static pos_t *get_pos(pos_t *from)
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{
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pos_t *new;
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if (!(new = pool_get(pool_pos)))
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return NULL;
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if (!from) {
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new->amp[0] = new->amp[1] = new->amp[2] = new->amp[3] = 0;
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new->moves = 0;
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new->cost = new->occupied = new->available = 0;
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} else {
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*new = *from;
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}
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INIT_LIST_HEAD(&new->list_pos);
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return new;
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}
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static u64 move_up(pos_t *pos, int amphipod)
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{
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pos_t newpos = *pos;
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u64 new, tmp, occupied = 0;
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new = pos->amp[amphipod] << 16;
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log(1, "********* moving %c up\n", amphipod + 'A');
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for (int i = 0; i < 4; ++i) {
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occupied |= pos->amp[i];
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}
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log(1, "occupied:\n");
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mask_print(occupied);
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log(1, "current occupation:\n");
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mask_print(pos->amp[amphipod]);
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log(1, "new occupation:\n");
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mask_print(new);
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tmp = new & ALLOWED;
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if (tmp != new)
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log(1, "%c cannot go up (forbidden)\n", amphipod + 'A');
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tmp = new & ~occupied;
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if (tmp != new)
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log(1, "%c cannot go up (occupied)\n", amphipod + 'A');
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newpos.amp[amphipod] = new & ALLOWED & ~occupied;
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//burrow_print(&newpos);
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return newpos.amp[amphipod];
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}
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static u64 move_down(pos_t *pos, int amphipod)
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{
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pos_t newpos = *pos;
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u64 new;
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log(1, "********* moving %c down\n", amphipod + 'A');
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new = pos->amp[amphipod] >> 16;
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printf("occupied\n");
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mask_print(pos->occupied);
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printf("available\n");
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mask_print(pos->available);
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newpos.amp[amphipod] = new & pos->available;
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return newpos.amp[amphipod];
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}
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static u64 move_left(pos_t *pos, int amphipod)
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{
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pos_t newpos = *pos;
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u64 new, tmp, occupied = 0;
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new = pos->amp[amphipod] << 1;
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log(1, "********* moving %c left\n", amphipod + 'A');
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for (int i = 0; i < 4; ++i) {
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occupied |= pos->amp[i];
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}
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log(1, "occupied:\n");
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mask_print(occupied);
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log(1, "current occupation:\n");
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mask_print(pos->amp[amphipod]);
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log(1, "new occupation:\n");
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mask_print(new);
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tmp = new & ALLOWED;
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if (tmp != new)
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log(1, "%c cannot go left (forbidden)\n", amphipod + 'A');
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tmp = new & ~occupied;
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if (tmp != new)
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log(1, "%c cannot go left (occupied)\n", amphipod + 'A');
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newpos.amp[amphipod] = new & ALLOWED & ~occupied;
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//burrow_print(&newpos);
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return newpos.amp[amphipod];
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}
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static u64 move_right(pos_t *pos, int amphipod)
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{
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pos_t newpos = *pos;
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u64 new;
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log(1, "********* moving %c right\n", amphipod + 'A');
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new = pos->amp[amphipod] >> 1;
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printf("occupied\n");
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mask_print(pos->occupied);
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printf("available\n");
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mask_print(pos->available);
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newpos.amp[amphipod] = new & ALLOWED & pos->available;
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return newpos.amp[amphipod];
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}
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/* minimal parsing: We just read the 3-5 lines to get
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* the amphipods location in side rooms
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*/
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static void read_input()
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{
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size_t alloc = 0;
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ssize_t buflen;
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char *buf = NULL;
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int line = 0;
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pos_t *pos = get_pos(NULL);
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while ((buflen = getline(&buf, &alloc, stdin)) > 0) {
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buf[--buflen] = 0;
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printf("line=%d str=%s\n", line, buf);
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if (line == 2 || line == 3) {
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u64 bit = 45 - 16 * (line - 2);
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//printf("bit = %d\n", bit);
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for (int i=0; i < 4; ++i) {
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int amp = buf[i * 2 + 3] - 'A';
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//printf("bit = %lu char = %c\n", bit, amp + 'A');
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pos->amp[amp] |= 1UL << bit;
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bit -= 2;
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}
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}
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line++;
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}
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pos->occupied = get_occupancy(pos);
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pos->available = ALLOWED & ~pos->occupied;
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burrow_print(pos);
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for (int i = 0; i < 4; ++i) {
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mask_print(move_up(pos, i));
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mask_print(move_left(pos, i));
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mask_print(move_down(pos, i));
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mask_print(move_right(pos, i));
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}
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free(buf);
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}
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static s64 part1()
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{
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return 1;
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}
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static s64 part2()
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{
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return 2;
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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, part = 1;
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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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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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pool_pos = pool_create("pos", 1024, sizeof(pos_t));
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read_input();
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printf("%s : res=%ld\n", *av, part == 1? part1(): part2());
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exit(0);
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}
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