110 lines
2.7 KiB
C
110 lines
2.7 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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#define ISDIGIT(c) (c >= 0x30 && c <= 0x39)
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inline uint64_t parse_number(const char *end);
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int main(int argc, char **argv) {
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FILE *input;
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size_t line_buf_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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char *time_line = NULL, *distance_line = NULL;
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ssize_t time_line_length = 0, distance_line_length = 0;
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if ((time_line_length = getline(&time_line, &line_buf_length, input)) == -1) {
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fprintf(stderr, "No time line in a file %s.", argv[1]);
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return -1;
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}
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if ((distance_line_length = getline(&distance_line, &line_buf_length, input)) == -1) {
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fprintf(stderr, "No distance line in a file %s.", argv[1]);
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return -1;
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}
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uint64_t *times = (uint64_t *) calloc(2, sizeof(uint64_t));
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uint64_t *distances = (uint64_t *) calloc(2, sizeof(uint64_t));
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ssize_t times_length = 2, distances_length = 2;
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for (ssize_t i = time_line_length-2, j = 0;;) {
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while (!ISDIGIT(time_line[i]))
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if (time_line[--i] == ':')
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goto tl_end;
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if (j == times_length)
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times = (uint64_t *) realloc(times, ++times_length * sizeof(uint64_t));
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times[j++] = parse_number(time_line+i);
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while(ISDIGIT(time_line[i])) --i;
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}
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tl_end:
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for (ssize_t i = distance_line_length-2, j = 0;;) {
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while (!ISDIGIT(distance_line[i]))
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if (distance_line[--i] == ':')
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goto dl_end;
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if (j == distances_length)
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distances = (uint64_t *) realloc(distances, ++distances_length * sizeof(uint64_t));
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distances[j++] = parse_number(distance_line+i);
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while(ISDIGIT(distance_line[i])) --i;
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}
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dl_end:
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uint64_t total_ways = 1;
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for (ssize_t i = 0; i < times_length; ++i) {
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uint64_t tmid = times[i] / 2;
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uint64_t ways = 0;
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for (uint64_t ht = tmid; ht <= times[i]; ++ht)
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if (ht * (times[i] - ht) > distances[i])
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++ways;
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else
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break;
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for (uint64_t ht = tmid-1; ht != 0; --ht)
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if (ht * (times[i] - ht) > distances[i])
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++ways;
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else
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break;
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total_ways *= ways;
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}
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free(times);
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free(distances);
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printf("%lu\n", total_ways);
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return 0;
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}
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inline uint64_t parse_number(const char *end) {
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uint64_t num = 0;
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for (size_t m = 1;; m *= 10) {
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if (*end>>4 != 0x3)
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break;
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num += (*end&0xf) * m;
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--end;
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}
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return num;
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} |