13b.c

   1 #include <stdio.h>
   2 #include <stdbool.h>
   3
   4 #include <uthash.h>
   5
   6 struct point { int x; int y; };
   7 struct dot { struct point p; UT_hash_handle hh; };
   8
   9 #define pnt(px, py) ((struct point){.x=(px), .y=(py)})
  10
  11 void add_dot(struct dot **grid, struct point p)
  12 {
  13         struct dot *d;
  14         HASH_FIND(hh, *grid, &p, sizeof(struct point), d);
  15         if (!d) {
  16                 d = malloc(sizeof(struct dot));
  17                 d->p = p;
  18                 HASH_ADD(hh, *grid, p, sizeof(struct point), d);
  19         }
  20 }
  21
  22 #define foldp(p, f) ( (f) - ( (p) - (f) ) )
  23
  24 void fold(struct dot **grid, char axis, int num)
  25 {
  26         struct dot *d, *tmp;
  27         HASH_ITER(hh, *grid, d, tmp) {
  28                 struct point p = d->p;
  29                 if (axis == 'x' && p.x >= num) {
  30                         HASH_DEL(*grid, d);
  31                         if (p.x > num)
  32                                 add_dot(grid, pnt(foldp(p.x, num), p.y));
  33                 } else if (axis == 'y' && p.y >= num) {
  34                         HASH_DEL(*grid, d);
  35                         if (p.y > num)
  36                                 add_dot(grid, pnt(p.x, foldp(p.y, num)));
  37                 }
  38         }
  39 }
  40
  41 int main()
  42 {
  43         char *buf = NULL;
  44         size_t len = 0;
  45         struct dot *grid = NULL;
  46
  47         while (getline(&buf, &len, stdin) != -1 && strcmp(buf, "\n") != 0) {
  48                 char *to = strchr(buf, ',');
  49                 *(to++)= '\0';
  50                 add_dot(&grid, pnt(atoi(buf), atoi(to)));
  51         }
  52         while (getline(&buf, &len, stdin) != -1) {
  53                 char *to = strchr(buf, '=');
  54                 fold (&grid, *(to-1), atoi(to+1));
  55         }
  56
  57         int maxx = 0, maxy = 0;
  58         for (struct dot *d = grid; d!=NULL; d = d->hh.next) {
  59                 maxx = maxx < d->p.x ? d->p.x : maxx;
  60                 maxy = maxy < d->p.y ? d->p.y : maxy;
  61         }
  62
  63         struct dot *d;
  64         for (int y = 0; y<=maxy; y++) {
  65                 for (int x = 0; x<=maxx; x++) {
  66                         HASH_FIND(hh, grid, &pnt(x, y), sizeof(struct point), d);
  67                         printf("%c", d ? '#' : '.');
  68                 }
  69                 printf("\n");
  70         }
  71 }