sdcc/support/regression/qct/0041-queen.c

   1
   2 int *calloc(int, int);
   3
   4 int N;
   5 int *t;
   6
   7 int
   8 chk(int x, int y)
   9 {
  10         int i;
  11         int r;
  12
  13         for (r=i=0; i<8; i++) {
  14                 r = r + t[x + 8*i];
  15                 r = r + t[i + 8*y];
  16                 if (x+i < 8 & y+i < 8)
  17                         r = r + t[x+i + 8*(y+i)];
  18                 if (x+i < 8 & y-i >= 0)
  19                         r = r + t[x+i + 8*(y-i)];
  20                 if (x-i >= 0 & y+i < 8)
  21                         r = r + t[x-i + 8*(y+i)];
  22                 if (x-i >= 0 & y-i >= 0)
  23                         r = r + t[x-i + 8*(y-i)];
  24         }
  25         return r;
  26 }
  27
  28 int
  29 go(int n, int x, int y)
  30 {
  31         if (n == 8) {
  32                 N++;
  33                 return 0;
  34         }
  35         for (; y<8; y++) {
  36                 for (; x<8; x++)
  37                         if (chk(x, y) == 0) {
  38                                 t[x + 8*y]++;
  39                                 go(n+1, x, y);
  40                                 t[x + 8*y]--;
  41                         }
  42                 x = 0;
  43         }
  44 }
  45
  46 int
  47 main()
  48 {
  49         t = calloc(64, sizeof(int));
  50         go(0, 0, 0);
  51         if(N != 92)
  52                 return 1;
  53         return 0;
  54 }
  55