//---------------------------------------------------
// Purpose: To implement the game "keep away chess"
//          using 2D arrays and functions.
// Authors: John Gauch
//---------------------------------------------------

#include <iostream>
using namespace std;

// Program constants
const int ROWS = 8;
const int COLS = 8;

//---------------------------------------------------
// Print the 2D game board 
//---------------------------------------------------
void print_board(char board[ROWS][COLS])
{
   // Print values
   cout << "     ";
   for (int col = 0; col < COLS; col++)
      cout << col << "   ";
   cout << endl;

   // Print line
   cout << "   +";
   for (int col = 0; col < COLS; col++)
      cout << "---+";
   cout << "\n";

   // Print board
   for (int row = 0; row < ROWS; row++)
   {
      // Print values
      cout << " " << row << " | ";
      for (int col = 0; col < COLS; col++)
         cout << board[row][col] << " | ";
      cout << endl;

      // Print line
      cout << "   +";
      for (int col = 0; col < COLS; col++)
         cout << "---+";
      cout << "\n";
   }
}

//---------------------------------------------------
// Check rows and columns for another chess piece
//---------------------------------------------------
bool check_board(char board[ROWS][COLS], 
   const int my_row, const int my_col)
{
   bool safe = true;

   // Check row
   for (int col = 0; col < COLS; col++)
      if (board[my_row][col] != ' ')
         safe = false;

   // Check column
   for (int row = 0; row < ROWS; row++)
      if (board[row][my_col] != ' ')
         safe = false;

   // Check diagonals (long slow way)
   for (int count = 0; count < ROWS; count++)
   {
      if ((my_row+count < ROWS) && (my_col+count < COLS))
         if (board[my_row+count][my_col+count] != ' ')
            safe = false;

      if ((my_row+count < ROWS) && (my_col-count >= 0))
         if (board[my_row+count][my_col-count] != ' ')
            safe = false;

      if ((my_row-count >= 0) && (my_col+count < COLS))
         if (board[my_row-count][my_col+count] != ' ')
            safe = false;

      if ((my_row-count >= 0) && (my_col-count >= 0))
         if (board[my_row-count][my_col-count] != ' ')
            safe = false;
   }

   // Check diagonals (short slow way)
   for (int row = 0; row < ROWS; row++)
      for (int col = 0; col < COLS; col++)
         if (row+col == my_row+my_col || row-col == my_row-my_col) 
            if (board[row][col] != ' ')
               safe = false;

   // Return result
   return safe;
}

//---------------------------------------------------
// Main program
//---------------------------------------------------
int main()
{
   // Define game board
   char board[ROWS][COLS];
   for (int row = 0; row < ROWS; row++)
      for (int col = 0; col < COLS; col++)
         board[row][col] = ' ';

   // Print game board
   print_board(board);

   // Loop playing game
   bool safe = true;
   while (safe)
   {
      // Get user input
      cout << "Enter row and col: ";
      int my_row, my_col;
      cin >> my_row >> my_col;
   
      // Put queen on board
      safe = check_board(board, my_row, my_col);
      if (safe)
         board[my_row][my_col] = 'Q';
      else
         board[my_row][my_col] = 'X';

      // Print game board
      print_board(board);
   }

   return 0;
}