90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
#define _GNU_SOURCE
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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 <stdint.h>
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#include <stdbool.h>
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#define STACK_SZ UINT8_MAX+1
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typedef uint8_t stackpointer_t;
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uint64_t parse_number(char *end);
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int main(int argc, char **argv) {
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FILE *input;
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char *line = NULL;
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size_t line_length = 0;
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if (argc == 1 || argv[1][0] == '-')
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input = stdin;
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else if ((input = fopen(argv[1], "r")) == NULL) {
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fprintf(stderr, "Cannot open file %s\n", argv[1]);
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return -1;
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}
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uint64_t total_copies = 0;
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size_t winning_numbers_len = 0;
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uint8_t *winning_numbers = NULL;
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char *colon_pos = NULL, *pipe_pos = NULL;
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uint64_t stack[STACK_SZ] = {0};
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stackpointer_t stack_pos = 0;
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while (getline(&line, &line_length, input) != -1) {
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colon_pos = strchr(line, ':');
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pipe_pos = strchr(line, '|');
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if (winning_numbers == NULL) {
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winning_numbers_len = (pipe_pos - colon_pos - 2) / 3;
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winning_numbers = (uint8_t *) calloc(winning_numbers_len, sizeof(uint8_t));
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}
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for (size_t i = 0, wl_pos = (size_t)colon_pos+4; i < winning_numbers_len; ++i, wl_pos += 3) {
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winning_numbers[i] = parse_number((char *)(wl_pos-1));
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}
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uint64_t card_copies = 1 + stack[stack_pos++];
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total_copies += card_copies;
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size_t old_sp = stack_pos;
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for (char *n_pos = pipe_pos + 4;; n_pos += 3) {
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uint8_t n = parse_number(n_pos-1);
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for (size_t i = 0; i < winning_numbers_len; ++i) {
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if (n != winning_numbers[i])
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continue;
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stack[stack_pos++] += card_copies;
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break;
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}
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if (*n_pos == '\n')
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break;
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}
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stack_pos = old_sp;
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memset(line, 0, line_length);
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}
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free(winning_numbers);
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printf("%lu\n", total_copies);
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return 0;
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}
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uint64_t parse_number(char *end) {
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uint64_t num = 0;
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for (size_t n = 1;; n *= 10) {
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if (*end>>4 != 0x3)
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break;
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num += (*end&0xf) * n;
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--end;
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}
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return num;
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} |