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