Fancy_8Queens.cpp

#include <iostream>
#include <cmath>
#include <cstdlib>
using namespace std;

bool ok(int q[], int c) {
   for (int i = 0; i < c; ++i)
      if (q[i] == q[c] || abs(q[i] - q[c]) == c - i)
         return false;
   return true;
}
void backtrack(int &col){
    col--;
    if(col == -1)
        exit(1);
}
void print(int q[]) {
   int i, j, k, l;
   typedef char box[5][7];   // box is now a data type: a 5x7 2D array of characters
   box bb, wb, *board[8][8]; // bb and wb are boxes (5x7 arrays).  board is an 8x8 array of pointers to boxes.
                             // You don't have to clean up the board after printing, because it's not static,
                             // so it'll be reinitialized the next time you call the funtion.

   // Fill in bb (black box) and wb (white box).  They each represent a square of the chessboard.
   // You only need to create one of each, since the chessboard can contain many pointers to the same box.
   for (i=0; i<5; i++)
      for (j=0; j<7; j++) {
         bb[i][j] = ' ';
         wb[i][j] = char(219);
      }

   // Create 2 more boxes to represent the queens, by drawing a picture of each queen in the 2D array.
   static box bq = { {char(219),char(219),char(219),char(219),char(219),char(219),char(219)},
                     {char(219),' '      ,char(219),' '      ,char(219),' '      ,char(219)},
                     {char(219),' '      ,' '      ,' '      ,' '      ,' '      ,char(219)},
                     {char(219),' '      ,' '      ,' '      ,' '      ,' '      ,char(219)},
                     {char(219),char(219),char(219),char(219),char(219),char(219),char(219)} };

   static box wq = { {' '      ,' '      ,' '      ,' '      ,' '      ,' '      ,' '      },
                     {' '      ,char(219),' '      ,char(219),' '      ,char(219),' '      },
                     {' '      ,char(219),char(219),char(219),char(219),char(219),' '      },
                     {' '      ,char(219),char(219),char(219),char(219),char(219),' '      },
                     {' '      ,' '      ,' '      ,' '      ,' '      ,' '      ,' '      } };

   // Fill board with pointers to bb and wb in alternate positions.
   for(i=0; i<8; i++)
      for(j=0; j<8; j++)
         if((i+j)%2 == 0)
            board[i][j] = &wb;
         else
            board[i][j] = &bb;
      //q[k] is the row the queen is in, k is the column the queen is in
      //if the column + row where queen is in is even then bq else wq
      //board[q[k][k] = the location of the queen on the board.
	  for(int k =0; k < 8; k++){
             if((k+q[k])%2 == 0)
         	board[q[k]][k] = &bq;
             else
		board[q[k]][k] = &wq;
      }

   // Set up the current solution on the chessboard by placing pointers to bq and wq in the appropriate squares.
   // Place black queens on white squares and white queens on black squares, so that you will be able to see them when printing.
   // Write the code.


   // Print upper border
   for (i=0; i<7*8; i++)
      cout << '_';
   cout << "\n";

   // Print the board
   for (i=0; i<8; i++)          // for each board row
      for (k=0; k<5; k++) {     // for each box row
         cout << char(179);
         for (j=0; j<8; j++)    // for each board column
            for (l=0; l<7; l++) // for each box column
               // board[i][j] is the box pointer in the ith row, jth column of the board.
               // *board[i][j] is the box being pointed to.
               // (*board[i][j])[k][l] is the kth row, lth column of the box.
               cout << (*board[i][j])[k][l];
         cout << char(179) << "\n";
      }

   // Print lower border
   cout << " ";
   for (i=0; i<7*8; i++)
      cout << char(196);
   cout << "\n\n";
}
int main(){
	 int q[8]; q[0]=0;
    int solution= 1;
    /*board setup section*/
    int c=0;
    bool from_backtrack=false;
    while(true){
        //next col
        while(c<8){
            if(!from_backtrack){
                c++;
                if(c==8)
                    break;
                q[c] = -1;


            }
            from_backtrack=false;

            while(q[c]<8){
                q[c]++;
                if(q[c] == 8){
                     backtrack(c);
                     from_backtrack=true;
                }

                if(ok(q, c))
                     break;




            }
        }
        cout << "solution #" <<solution << endl;
        print(q) ;
        solution = solution + 1;
        backtrack(c);
        from_backtrack=true;
    }
}