s: make_random_state(true);
set_random_state(s);

f(x, y) := block([dx, dy],
	dx: divide(x + 2, 3),
	dy: divide(y + 2, 3),
	[dx[1] * 3 + dy[1] - 3, dx[2] * 3 + dy[2] + 1]
);

sudoku() := ([n: 100,
	M: zeromatrix(9, 9), 
	K: zeromatrix(9, 9),
	T: zeromatrix(9, 9)],
	if not (integerp(x) and x > 0) then x: 10,
	for l: 1 while (l <= 9 and n >= 0) do (
		n: n - 1,
		q: 0,
		for i: 1 while(i <= 9 and q = 0) do (
			p: 0,
			for j: 1 while (p = 0 and q = 0) do (
				a: random(9) + 1,
				if not member(0, K[i]) then (
					q: 1,
					l: l - 1,
					K: copymatrix(T),
					M: copymatrix(T)
				) else 
				if K[i][a] = 0 then (
					p: 1,
					for k: 1 thru 9 do (
						d: f(f(i, a)[1], k),
						K[d[1]][d[2]]: 1
					),
					for k: 1 thru 9 do K[k][a]: 1,
					M[i][a]: l
				)
			)
		),
		K: copymatrix(M),
		T: copymatrix(M)
	),
	if n < 0 then n else M
);