// CS 1711B, November 25, 1998
// places queens on a chess board


#include <iostream.h>

void clear_board(char brd[][8]);
// places . in all of brd[i][j]


void place_queen(char brd[][8], int row, int col);
// places queen in position row,col of brd if the space is unused
// marks protected squares
// does nothing if position is occupied


int board_empty(const char brd[][8], int row, int col);
// tests whether brd[row][col] is a .

void display_board(const char brd[][8]);
// displays brd to screen


int main()
{  char brd[8][8];
   char resp;  // continue placing?
   int row, col;

   clear_board(brd);
//   display_board(brd);

   do{
   cout << "\nwhat row and column? (between 1 and 8)?\n";
   cin >> row >> col;
   row--; col--; //decrement to place between 0 and 7

   place_queen(brd,row,col);
   display_board(brd);

   cout << "\nanother?\n";
   cin >> resp;
   }
   while((resp == 'y')||(resp=='Y'));
   return 0;
}

void clear_board(char brd[][8])
{
int i,j;

for(i = 0; i <8; i++)
 { for(j = 0; j <8; j++)
	{ brd[i][j] = '.';}
  }
}


void place_queen(char brd[][8], int row, int col)
{
 int i,j,u,d,l,r;
 if(board_empty(brd,row,col))  // do place queen
   {
   // marks row, then column...
	 for(j = 0; j <8; j++)
		{ if (brd[row][j] == '.') brd[row][j] = 'X';}
	 for(i = 0; i <8; i++)
		{ if (brd[i][col] == '.') brd[i][col] = 'X';}
   // marks diagonals, first u(p) and l(eft)...
	 u = row-1; l = col-1;
	 while((u >=0)&&(l>=0))
		{ if (brd[u][l] == '.') brd[u][l] = 'X';
		  u--; l--;
		}
   // then u(p) and r(ight)...
	 u = row-1; r = col+1;
	 while((u >=0)&&(r < 8))
		{ if (brd[u][r] == '.') brd[u][r] = 'X';
		  u--; r++;
		}
   // d(own) and ...
	 d = row+1; l = col-1;
	 while((d < 8)&&(l >= 0))
		{ if (brd[d][l] == '.') brd[d][l] = 'X';
		  d++; l--;
		}


	 d = row+1; r = col+1;
	 while((d < 8)&&(r < 8))
		{ if (brd[d][r] == '.') brd[d][r] = 'X';
		  d++; r++;
		}
   // finally queen is placed
	 brd[row][col] = 'Q';
   }
  else
   cout << "\nThere was no change\n";
}

int board_empty(const char brd[][8], int row, int col)
{
 if(brd[row][col] == '.')
   return 1;
 else
   return 0;

}

void display_board(const char brd[][8])
{
int i,j;

cout << endl;

for(i = 0; i <8; i++)
 { for(j = 0; j <8; j++)
	{ cout << " " << brd[i][j];}
   cout << endl;
  }

}