05b.c

   1 #include <stdio.h>
   2 #include <uthash.h>
   3
   4 #define SWAP(x, y) { x ^= y; y ^= x; x ^= y; }
   5
   6 struct point { int x; int y; };
   7 struct entry { struct point key; int i; UT_hash_handle hh; };
   8
   9 void mark_point(int x, int y, struct entry **entries, int *r)
  10 {
  11         struct entry *p;
  12         struct point s;
  13         memset(&s, 0, sizeof s);
  14         s.x = x;
  15         s.y = y;
  16         HASH_FIND(hh, *entries, &s, sizeof(struct point), p);
  17         if (p) {
  18                 if (p->i++ == 1)
  19                         *r = *r+1;
  20         } else {
  21                 p = calloc(1, sizeof(struct entry));
  22                 p->key = s;
  23                 p->i = 1;
  24                 HASH_ADD(hh, *entries, key, sizeof(struct point), p);
  25         }
  26 }
  27
  28 int main()
  29 {
  30         char buf[1000];
  31         struct entry *entries = NULL;
  32         int r = 0;
  33         while (fgets(buf, 1000, stdin) != NULL) {
  34                 char *ptr = &buf[0];
  35                 int x1 = strtol(ptr, &ptr, 10);
  36                 ptr++;
  37                 int y1 = strtol(ptr, &ptr, 10);
  38                 ptr+=4;
  39                 int x2 = strtol(ptr, &ptr, 10);
  40                 ptr++;
  41                 int y2 = strtol(ptr, &ptr, 10);
  42
  43                 //Diagonal
  44                 if (abs(y2-y1) == abs(x2-x1)) {
  45                         int dx = x1 > x2 ? -1 : 1;
  46                         int dy = y1 > y2 ? -1 : 1;
  47                         for (; x1 != x2; x1 += dx, y1+= dy)
  48                                 mark_point(x1, y1, &entries, &r);
  49                         mark_point(x1, y1, &entries, &r);
  50                 } else {
  51                         if (x1 > x2)
  52                                 SWAP(x1, x2);
  53                         if (y1 > y2)
  54                                 SWAP(y1, y2);
  55                         //Vertical
  56                         if (x1 == x2)
  57                                 for (int y = y1; y<=y2; y++)
  58                                         mark_point(x1, y, &entries, &r);
  59                         //Horizontal
  60                         else if (y1 == y2)
  61                                 for (int x = x1; x<=x2; x++)
  62                                         mark_point(x, y1, &entries, &r);
  63                 }
  64         }
  65         printf("%d\n", r);
  66 }