2019/day1.c

   1 #define _GNU_SOURCE 1
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include <stdarg.h>
   6 #include <stdbool.h>
   7
   8 void debug(const char *fmt, ...) {
   9   va_list ap;
  10   if (getenv("DEBUG")) {
  11     va_start(ap, fmt);
  12     vfprintf(stderr, fmt, ap);
  13     va_end(ap);
  14   }
  15 }
  16
  17 int main(int argc, char **argv) {
  18   size_t len = 0, count = 0;
  19   int i, sum1 = 0, sum2 = 0;
  20   char *line;
  21
  22   if (argc > 1)
  23     if (!(stdin = freopen(argv[1], "r", stdin))) {
  24       perror("failure");
  25       exit(2);
  26     }
  27
  28   while (getline(&line, &len, stdin) >= 0) {
  29     ++count;
  30     i = atoi(line);
  31     if (i < 6) {
  32       fprintf(stderr, "bad input\n");
  33       exit(1);
  34     }
  35     sum1 += i / 3 - 2;
  36     while (i > 8) {
  37       sum2 += i / 3 - 2;
  38       i = i / 3 - 2;
  39     }
  40   }
  41   printf("Read %zu lines, sum1 %d, sum2 %d\n", count, sum1, sum2);
  42   return 0;
  43 }