2018/day3a.c

   1 #define _GNU_SOURCE 1
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <stdlib.h>
   5 #include <stdarg.h>
   6
   7 void debug(const char *fmt, ...) {
   8   va_list ap;
   9   if (getenv("DEBUG")) {
  10     va_start(ap, fmt);
  11     vfprintf(stderr, fmt, ap);
  12     va_end(ap);
  13   }
  14 }
  15
  16 #define LIMIT 1000
  17
  18 char array[LIMIT][LIMIT];
  19
  20 static void process(const char *str) {
  21   int a, b, c, d, e;
  22   int i, j;
  23   if (sscanf(str, "#%d @ %d,%d: %dx%d\n", &a, &b, &c, &d, &e) != 5) {
  24     printf("bad input!\n");
  25     exit(1);
  26   }
  27   if (b + d > LIMIT || c + e > LIMIT) {
  28     printf("recompile with larger LIMIT!\n");
  29     exit(1);
  30   }
  31   debug("processing %d,%d: %dx%d\n", b, c, d, e);
  32   for (i = b; i < b + d; i++)
  33     for (j = c; j < c + e; j++)
  34       array[j][i]++;
  35 }
  36
  37 int main(int argc, char **argv) {
  38   size_t len = 0, count = 0;
  39   char *line;
  40   int i, j;
  41
  42   if (argc > 1)
  43     if (!(stdin = freopen(argv[1], "r", stdin))) {
  44       perror("failure");
  45       exit(2);
  46     }
  47
  48   while (getline(&line, &len, stdin) >= 0) {
  49     count++;
  50     process(line);
  51   }
  52   printf("read %zd lines\n", count);
  53   count = 0;
  54   for (i = 0; i < LIMIT; i++)
  55     for (j = 0; j < LIMIT; j++) {
  56       debug("%d %d %d\n", i, j, array[j][i]);
  57       if (array[j][i] > 1)
  58         count++;
  59     }
  60   printf("found %zd overlaps\n", count);
  61   return 0;
  62 }