<p>An array with destructive updates (IO/ST) may help. You can also look into the exact cover problem and dancing links. If I recall correctly, this problem can be transformed to a 729*324 matrix.</p>
<div class="gmail_quote">在 2012-1-3 上午8:10，"Peter Hall" <<a href="mailto:peter.hall@memorphic.com">peter.hall@memorphic.com</a>>写道：<br type="attribution"></div>