commit 748af4eff54eaf7ac72479c7257d72b04f581153
parent 57904a31a238de8b9bae1cec57b267d4b53c886a
Author: amin <dev@aminmesbah.com>
Date: Sat, 4 Dec 2021 23:46:13 +0000
Solve 2021 day 4 part 2
FossilOrigin-Name: fe3ef5ff4487d6ae6077b073d9b006bbc887c32f8e0c74fe346d1c8182150819
Diffstat:
| A | 2021/day04_02.c | | | 182 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 182 insertions(+), 0 deletions(-)
diff --git a/2021/day04_02.c b/2021/day04_02.c
@@ -0,0 +1,182 @@
+#if 0
+# Self-building c file. Invoke like: `./file.c`
+outdir=out
+input=$(basename "$0")
+output="$outdir"/$(basename "$0" .c)
+if [ "$input" -nt "$output" ];
+then
+ mkdir --parents "$outdir" || exit
+ echo "Building ${output}." || exit
+ clang -std=c11 -Wall -Wextra -pedantic -Wno-unused-function "$input" -o "$output" || exit
+fi
+if [ "$1" = "-r" ];
+then
+ ./"$output" "$@"
+fi
+exit
+#endif
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+_Noreturn void assert_fail(const char *expr, const char *file, int line, const char *func) {
+ fprintf(stderr, "%s:%d: %s: Assertion failed: '%s'\n", file, line, func, expr);
+ abort();
+}
+
+#define AM_ENABLE_ASSERT 1
+#define AM_ASSERT_FAIL(expr, file, line, func) assert_fail(expr, file, line, func)
+#include "am_base.h"
+#include "am_memory.h"
+#include "am_list.h"
+#include "am_string.h"
+
+Str open_file(MemArena *arena, char *path) {
+ FILE *f = fopen(path, "r");
+ assert(f);
+
+ s32 error = fseek(f, 0L, SEEK_END);
+ assert(!error);
+
+ s64 size = ftell(f);
+ assert(size >= 0);
+ rewind(f);
+
+ u8 *buf = am_mem_arena_push(arena, size);
+ assert(buf);
+
+ size_t items_read = fread(buf, 1, size, f);
+ assert(items_read == (size_t)size);
+
+ error = fclose(f);
+ assert(!error);
+
+ return am_str(buf, size);
+}
+
+int compare_u64(const void *a, const void *b) {
+ u64 num_a = *((u64 *)a);
+ u64 num_b = *((u64 *)b);
+ if (num_a == num_b) {
+ return 0;
+ } else if (num_a < num_b) {
+ return -1;
+ } else {
+ return 1;
+ }
+}
+
+s64 parse_number(Str s) {
+ s64 number = 0;
+ for (u64 i = 0; i < s.size; i++) {
+ assert(s.str[i] >= '0' && s.str[i] <= '9');
+ number = (number * 10) + (s.str[i] - '0');
+ }
+ return number;
+}
+
+int main(void) {
+ MemArena a = am_mem_arena_create(am_mem_base_allocator_malloc());
+ Str input = open_file(&a, "day04_input.txt");
+
+ StrList split_data = am_str_split(&a, input, (u8 *)"\n ", 2);
+ StrList split_first_line = am_str_split(&a, split_data.first->s, (u8 *)",", 1);
+
+ u64 drawn_number_count = split_first_line.node_count;
+ u64 board_number_count = split_data.node_count - 1;
+ assert(board_number_count % 25 == 0);
+
+ s64 *drawn_numbers = AM_MEM_ARENA_PUSH_ARRAY(&a, s64, drawn_number_count);
+ s64 *board_numbers = AM_MEM_ARENA_PUSH_ARRAY(&a, s64, board_number_count);
+
+ {
+ u64 i = 0;
+ for (StrListNode *number = split_first_line.first; number; number = number->next) {
+ drawn_numbers[i] = parse_number(number->s);
+ i++;
+ }
+ assert(i == drawn_number_count);
+ }
+
+ {
+ u64 i = 0;
+ for (StrListNode *number = split_data.first->next; number; number = number->next) {
+ board_numbers[i] = parse_number(number->s);
+ i++;
+ }
+ assert(i == board_number_count);
+ }
+
+ u64 winning_score = 0;
+ u64 win_count = 0;
+ u64 board_count = board_number_count / 25;
+ bool *board_win_status = AM_MEM_ARENA_PUSH_ARRAY(&a, bool, board_count);
+ memset(board_win_status, 0, board_count * sizeof(bool));
+
+ for (u64 drawn_i = 0; drawn_i < drawn_number_count; drawn_i++) {
+ s64 drawn = drawn_numbers[drawn_i];
+
+ for (u64 board_i = 0; board_i < board_number_count; board_i++) {
+ if (board_numbers[board_i] == drawn) {
+ board_numbers[board_i] = -1;
+ }
+ }
+
+ u8 row_count = 0;
+ u8 col_count[5] = {0};
+ for (u64 board_i = 0; board_i < board_number_count; board_i++) {
+ u64 board = board_i / 25;
+ if (board_win_status[board]) {
+ continue;
+ }
+
+ u64 cell = board_i % 25;
+ u64 row = cell / 5;
+ u64 col = cell % 5;
+
+ row_count += board_numbers[board_i] == -1;
+ col_count[col] += board_numbers[board_i] == -1;
+
+ bool game_won = false;
+ if ((cell + 1) / 5 != row) {
+ if (row_count == 5) {
+ game_won = true;
+ }
+ row_count = 0;
+ }
+
+ if (row == 4) {
+ if (col_count[col] == 5) {
+ game_won = true;
+ }
+ col_count[col] = 0;
+ }
+
+ if (game_won) {
+ board_win_status[board] = true;
+ win_count++;
+ if (win_count == board_count) {
+ for (u64 i = board * 25; i < board * 25 + 25; i++) {
+ winning_score += board_numbers[i] * (board_numbers[i] != -1);
+ }
+ winning_score *= drawn;
+ goto game_over;
+ }
+ row_count = 0;
+ memset(col_count, 0, 5);
+ }
+ }
+ }
+
+game_over:
+ if (win_count) {
+ printf("Winning score of last winning board: %" PRIu64 "\n", winning_score);
+ } else {
+ printf("No Winning Board!\n");
+ }
+
+ am_mem_arena_release(&a);
+ return 0;
+}
