2018/day3b.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 short array[LIMIT][LIMIT];
  19 char list[1500];
  20
  21 static void process(const char *str) {
  22   int a, b, c, d, e;
  23   int i, j;
  24   if (sscanf(str, "#%d @ %d,%d: %dx%d\n", &a, &b, &c, &d, &e) != 5) {
  25     printf("bad input!\n");
  26     exit(1);
  27   }
  28   if (b + d > LIMIT || c + e > LIMIT) {
  29     printf("recompile with larger LIMIT!\n");
  30     exit(1);
  31   }
  32   debug("processing #%d %d,%d: %dx%d\n", a, b, c, d, e);
  33   for (i = b; i < b + d; i++)
  34     for (j = c; j < c + e; j++) {
  35       if (array[j][i])
  36         list[a] = list[array[j][i]] = 1;
  37       else
  38         array[j][i] = a;
  39     }
  40 }
  41
  42 int main(int argc, char **argv) {
  43   size_t len = 0, count = 0;
  44   char *line;
  45   int i, j;
  46
  47   if (argc > 1)
  48     if (!(stdin = freopen(argv[1], "r", stdin))) {
  49       perror("failure");
  50       exit(2);
  51     }
  52
  53   while (getline(&line, &len, stdin) >= 0) {
  54     count++;
  55     process(line);
  56   }
  57   printf("read %zd lines\n", count);
  58   count = 0;
  59   for (i = 0; i < LIMIT; i++)
  60     for (j = 0; j < LIMIT; j++) {
  61       debug("%d %d %d\n", i, j, array[j][i]);
  62       if (array[j][i] > 1)
  63         count++;
  64     }
  65   printf("found %zd overlaps\n", count);
  66   for (i = 1; i < sizeof list; i++)
  67     if (!list[i])
  68       break;
  69   printf("unique claim %d\n", i);
  70   return 0;
  71 }