function sudoku
global board

% basic idea
% set up game
% get custom board
% play game
% show board
% solved?
% columns, rows, quads solved? (each checked incrementally)

another = true;
while another
  setUpGame();
  playGame();
  another = anotherGame();
end
return

function setUpGame()
global board
disp('Setting Up Game');
board(1:9,1:9) = ' ';
ans = input('Custom or Default Board? (0 custom, 1 default) ');
if ans == 0
  getCustomBoard();
else
  board = ['1   9   8'
           ' 897    3'
           ' 4     7 '
           '     294 '
           '   5 1   '
           ' 243     '
           ' 1     5 '
           '8    763 '
           '7   5   4']
end
return

function getCustomBoard()
global board
disp('Getting Custom Board');
disp('Enter each line with periods and numerals eg ..26...1.');
disp('        123456789');
for ii=1:9
  fprintf('line %1d', ii);
  board(ii,1:9) = input(': ','s');
end
mask = board == '.';
board(mask) = ' ';
return

function playGame()
global board
disp('Playing Game');
while ~solved()
  showBoard();
  choice = showMenu();
  switch choice
    case 1,
      makeGuess();
    case 2,
      getHint();
    otherwise,
      disp('Quitting!');
      break;
  end 
end
return

function showBoard()
global board
disp('Showing the Board');
fprintf('\n');
fprintf('+-----+-----+-----+\n');
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(1,1:9));
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(2,1:9));
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(3,1:9));
fprintf('+-----+-----+-----+\n');
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(4,1:9));
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(5,1:9));
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(6,1:9));
fprintf('+-----+-----+-----+\n');
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(7,1:9));
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(8,1:9));
fprintf('|%c %c %c|%c %c %c|%c %c %c|\n', board(9,1:9));
fprintf('+-----+-----+-----+\n');
fprintf('\n');
return

function choice = showMenu();
disp('Showing a Menu');
choice = input('1 - Make a guess, 2 - Get a hint, other - quit: ');
return

function done = solved()
disp('Solved?');
done = allColumnsDone() & allRowsDone() & allQuadsDone()
return

function done = allColumnsDone()
global board
disp('Columns done?');
a = sort(board,1)
n = ['1':'9']';
n = [n n n n n n n n n]
c = a == n
disp('What is sum?')
sum(sum(c))
done = sum(sum(c)) == 4293;
return

function done = allRowsDone()
global board
disp('Rows done?');
a = sort(board,2)
n = ['1':'9'];
n = [n;n;n;n;n;n;n;n;n]
c = a == n
done = sum(sum(c)) == 4293;
return

function done = allQuadsDone()
global board
disp('Quads done?');
n = ['1':'9'];
done = true;
for ii = 1:3:7
  for jj = 1:3:7
    q = board(ii:ii+2, jj:jj+2);
    q = q(1:9);
    q = sort(q)
    c = q == n
    done = done && sum(c) == 477;
  end
end
return

function makeGuess()
disp('Making a Guess');
return

function getHint()
disp('Get a Hint');
return

function another = anotherGame();
another = input('Play again?  (0 no, 1 yes) ');
return