<html>
<head>
<title>Su Doku</title>
<meta name="description" content="Sudoku">
<meta name="keywords" content="Sudoku">
</head>
<body>
<style>
.digit {
  margin : 0px 0px 0px 0px;
  padding : 3px 3px 3px 3px;
  background-color: cornflowerblue;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  color: #000000;
  font-size: 18pt;
  text-align: center;
  border: 0px none;
  width: 28pt;
}
.digitlock {
  margin : 0px 0px 0px 0px;
  padding : 3px 3px 3px 3px;
  background-color: cornflowerblue;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  color: cornflowerblue;
  font-size: 18pt;
  text-align: center;
  border: 0px none;
  width: 28pt;
}
.score {
  margin : 0px 0px 0px 0px;
  padding : 0px 0px 0px 0px;
  background-color: cornflowerblue;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  color: cornflowerblue;
  font-size: 16pt;
  text-align: center;
  border: 0px none;
}
.instr {
  margin : 0px 0px 0px 0px;
  padding : 0px 0px 0px 0px;
  background-color: cornflowerblue;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  color: cornflowerblue;
  font-size: 12pt;
  text-align: center;
  border: 0px none;
}
.target {
  margin : 0px 0px 0px 0px;
  padding : 0px 0px 0px 0px;
  background-color: cornflowerblue;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  color: cornflowerblue;
  font-size: 12pt;
  text-align: center;
  border: 0px none;
}
.bdigit {
  width: 50px;
  height: 30px;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  font-size: 12pt;
}
.bcontrol {
  width: 80px;
  height: 30px;
  font-family: verdana, tahoma, helvetica, arial, sans-serif;
  font-weight: bold;
  font-size: 12pt;
}
</style>
		



</script>
                







                          


<body onload="initialise()" onunload="saveboard()">

<p><center>
<h1 align=center>Su Doku Puzzle Creator</h1>
<form>
<p><center><table border=3 cellpadding=0 cellspacing=0 bgcolor="cornflowerblue">
<tr>
  <td rowspan=3 align=center width=100 valign=middle bgcolor="cornflowerblue">
  <h3>controls</h3>
  <input type="button" class="bcontrol" name="bcreate" value="Create" onclick="docreate()"><br>
  <input type="button" class="bcontrol" name="bclear" value="Clear" onclick="doclear()"><br>
  <input type="button" class="bcontrol" name="block" value="Lock" onclick="dolock()"><br>

  <input type="button" class="bcontrol" name="breset" value="Reset" onclick="doreset()"><br>
  <input type="button" class="bcontrol" name="breset" value="Hint" onclick="dohint()"><br>
  <input type="button" class="bcontrol" name="bsolve" value="Solve" onmousedown="dosolution(1)" onmouseup="dosolution(0)"><br>
  </td>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c0" value=" " size="1" readonly onclick="cell(0)" ></td>
<td><input class="digit" type="text" id="c1" value=" " size="1" readonly onclick="cell(1)" ></td>
<td><input class="digit" type="text" id="c2" value=" " size="1" readonly onclick="cell(2)" ></td>

	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c9" value=" " size="1" readonly onclick="cell(9)" ></td>
<td><input class="digit" type="text" id="c10" value=" " size="1" readonly onclick="cell(10)" ></td>
<td><input class="digit" type="text" id="c11" value=" " size="1" readonly onclick="cell(11)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c18" value=" " size="1" readonly onclick="cell(18)" ></td>
<td><input class="digit" type="text" id="c19" value=" " size="1" readonly onclick="cell(19)" ></td>
<td><input class="digit" type="text" id="c20" value=" " size="1" readonly onclick="cell(20)" ></td>
	  </tr>
    </table>

  </td>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c3" value=" " size="1" readonly onclick="cell(3)" ></td>
<td><input class="digit" type="text" id="c4" value=" " size="1" readonly onclick="cell(4)" ></td>
<td><input class="digit" type="text" id="c5" value=" " size="1" readonly onclick="cell(5)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c12" value=" " size="1" readonly onclick="cell(12)" ></td>
<td><input class="digit" type="text" id="c13" value=" " size="1" readonly onclick="cell(13)" ></td>

<td><input class="digit" type="text" id="c14" value=" " size="1" readonly onclick="cell(14)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c21" value=" " size="1" readonly onclick="cell(21)" ></td>
<td><input class="digit" type="text" id="c22" value=" " size="1" readonly onclick="cell(22)" ></td>
<td><input class="digit" type="text" id="c23" value=" " size="1" readonly onclick="cell(23)" ></td>
	  </tr>
    </table>
  </td>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>

	  <tr>
<td><input class="digit" type="text" id="c6" value=" " size="1" readonly onclick="cell(6)" ></td>
<td><input class="digit" type="text" id="c7" value=" " size="1" readonly onclick="cell(7)" ></td>
<td><input class="digit" type="text" id="c8" value=" " size="1" readonly onclick="cell(8)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c15" value=" " size="1" readonly onclick="cell(15)" ></td>
<td><input class="digit" type="text" id="c16" value=" " size="1" readonly onclick="cell(16)" ></td>
<td><input class="digit" type="text" id="c17" value=" " size="1" readonly onclick="cell(17)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c24" value=" " size="1" readonly onclick="cell(24)" ></td>

<td><input class="digit" type="text" id="c25" value=" " size="1" readonly onclick="cell(25)" ></td>
<td><input class="digit" type="text" id="c26" value=" " size="1" readonly onclick="cell(26)" ></td>
	  </tr>
    </table>
  </td>
  <td rowspan=3 align=center width=100 valign=middle bgcolor="cornflowerblue">
<input type="button" class="bdigit" name="but1" value="1" onclick="dodigit(0)"><br>
<input type="button" class="bdigit" name="but2" value="2" onclick="dodigit(1)"><br>
<input type="button" class="bdigit" name="but3" value="3" onclick="dodigit(2)"><br>
<input type="button" class="bdigit" name="but4" value="4" onclick="dodigit(3)"><br>
<input type="button" class="bdigit" name="but5" value="5" onclick="dodigit(4)"><br>
<input type="button" class="bdigit" name="but6" value="6" onclick="dodigit(5)"><br>
<input type="button" class="bdigit" name="but7" value="7" onclick="dodigit(6)"><br>

<input type="button" class="bdigit" name="but8" value="8" onclick="dodigit(7)"><br>
<input type="button" class="bdigit" name="but9" value="9" onclick="dodigit(8)"><br>
<input type="button" class="bdigit" name="but0" value="_" onclick="dodigit(15)"><br>

  </td>
</tr>
<tr>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c27" value=" " size="1" readonly onclick="cell(27)" ></td>
<td><input class="digit" type="text" id="c28" value=" " size="1" readonly onclick="cell(28)" ></td>
<td><input class="digit" type="text" id="c29" value=" " size="1" readonly onclick="cell(29)" ></td>

	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c36" value=" " size="1" readonly onclick="cell(36)" ></td>
<td><input class="digit" type="text" id="c37" value=" " size="1" readonly onclick="cell(37)" ></td>
<td><input class="digit" type="text" id="c38" value=" " size="1" readonly onclick="cell(38)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c45" value=" " size="1" readonly onclick="cell(45)" ></td>
<td><input class="digit" type="text" id="c46" value=" " size="1" readonly onclick="cell(46)" ></td>
<td><input class="digit" type="text" id="c47" value=" " size="1" readonly onclick="cell(47)" ></td>
	  </tr>
    </table>

  </td>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c30" value=" " size="1" readonly onclick="cell(30)" ></td>
<td><input class="digit" type="text" id="c31" value=" " size="1" readonly onclick="cell(31)" ></td>
<td><input class="digit" type="text" id="c32" value=" " size="1" readonly onclick="cell(32)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c39" value=" " size="1" readonly onclick="cell(39)" ></td>
<td><input class="digit" type="text" id="c40" value=" " size="1" readonly onclick="cell(40)" ></td>

<td><input class="digit" type="text" id="c41" value=" " size="1" readonly onclick="cell(41)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c48" value=" " size="1" readonly onclick="cell(48)" ></td>
<td><input class="digit" type="text" id="c49" value=" " size="1" readonly onclick="cell(49)" ></td>
<td><input class="digit" type="text" id="c50" value=" " size="1" readonly onclick="cell(50)" ></td>
	  </tr>
    </table>
  </td>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>

	  <tr>
<td><input class="digit" type="text" id="c33" value=" " size="1" readonly onclick="cell(33)" ></td>
<td><input class="digit" type="text" id="c34" value=" " size="1" readonly onclick="cell(34)" ></td>
<td><input class="digit" type="text" id="c35" value=" " size="1" readonly onclick="cell(35)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c42" value=" " size="1" readonly onclick="cell(42)" ></td>
<td><input class="digit" type="text" id="c43" value=" " size="1" readonly onclick="cell(43)" ></td>
<td><input class="digit" type="text" id="c44" value=" " size="1" readonly onclick="cell(44)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c51" value=" " size="1" readonly onclick="cell(51)" ></td>

<td><input class="digit" type="text" id="c52" value=" " size="1" readonly onclick="cell(52)" ></td>
<td><input class="digit" type="text" id="c53" value=" " size="1" readonly onclick="cell(53)" ></td>
	  </tr>
    </table>
  </td>
</tr>
<tr>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c54" value=" " size="1" readonly onclick="cell(54)" ></td>

<td><input class="digit" type="text" id="c55" value=" " size="1" readonly onclick="cell(55)" ></td>
<td><input class="digit" type="text" id="c56" value=" " size="1" readonly onclick="cell(56)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c63" value=" " size="1" readonly onclick="cell(63)" ></td>
<td><input class="digit" type="text" id="c64" value=" " size="1" readonly onclick="cell(64)" ></td>
<td><input class="digit" type="text" id="c65" value=" " size="1" readonly onclick="cell(65)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c72" value=" " size="1" readonly onclick="cell(72)" ></td>
<td><input class="digit" type="text" id="c73" value=" " size="1" readonly onclick="cell(73)" ></td>
<td><input class="digit" type="text" id="c74" value=" " size="1" readonly onclick="cell(74)" ></td>
	  </tr>

    </table>
  </td>
  <td valign=top>
    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c57" value=" " size="1" readonly onclick="cell(57)" ></td>
<td><input class="digit" type="text" id="c58" value=" " size="1" readonly onclick="cell(58)" ></td>
<td><input class="digit" type="text" id="c59" value=" " size="1" readonly onclick="cell(59)" ></td>
	  </tr>
	  <tr>

<td><input class="digit" type="text" id="c66" value=" " size="1" readonly onclick="cell(66)" ></td>
<td><input class="digit" type="text" id="c67" value=" " size="1" readonly onclick="cell(67)" ></td>
<td><input class="digit" type="text" id="c68" value=" " size="1" readonly onclick="cell(68)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c75" value=" " size="1" readonly onclick="cell(75)" ></td>
<td><input class="digit" type="text" id="c76" value=" " size="1" readonly onclick="cell(76)" ></td>
<td><input class="digit" type="text" id="c77" value=" " size="1" readonly onclick="cell(77)" ></td>
	  </tr>
    </table>
  </td>
  <td valign=top>

    <table border=1 cellpadding=0 cellspacing=0>
	  <tr>
<td><input class="digit" type="text" id="c60" value=" " size="1" readonly onclick="cell(60)" ></td>
<td><input class="digit" type="text" id="c61" value=" " size="1" readonly onclick="cell(61)" ></td>
<td><input class="digit" type="text" id="c62" value=" " size="1" readonly onclick="cell(62)" ></td>
	  </tr>
	  <tr>
<td><input class="digit" type="text" id="c69" value=" " size="1" readonly onclick="cell(69)" ></td>
<td><input class="digit" type="text" id="c70" value=" " size="1" readonly onclick="cell(70)" ></td>
<td><input class="digit" type="text" id="c71" value=" " size="1" readonly onclick="cell(71)" ></td>
	  </tr>
	  <tr>

<td><input class="digit" type="text" id="c78" value=" " size="1" readonly onclick="cell(78)" ></td>
<td><input class="digit" type="text" id="c79" value=" " size="1" readonly onclick="cell(79)" ></td>
<td><input class="digit" type="text" id="c80" value=" " size="1" readonly onclick="cell(80)" ></td>
	  </tr>
    </table>
  </td>
</tr>
</table></center>

<embed src="beep.wav" autostart=false hidden=true id="beep" enablejavascript="true">
</body>

<script>
// Sudoku Puzzle Creator & WorkPad
// (c) 2005 Mark Huckvale - University College London
//
// Revision history
//  1.0 - Initial Release
//  1.1 - Final animation
//  1.2 - Improved hint function, clear cell button
//
// global variables
var ccell;						// current cell for cursor
var board=new Array(81);		// board on display
var digit=new Array('1','2','3','4','5','6','7','8','9','*','*','*','*','*','*',' ');
var digit_mask=0x0000000F;		// displayed digit mask
var solve_mask=0x000000F0;		// solution digit mask
var allow_mask=0x0001FF00;		// digits allowed in this cell mask
var locks_mask=0x00020000;		// cell locked mask
var allow_bits=new Array(0x00100,0x00200,0x00400,0x00800,0x01000,0x02000,0x04000,0x08000,0x10000);
var lock_flag=0x00020000;		// cell locked
var box_index=new Array(9);		// look-up table for boxes
var col_index=new Array(9);		// look-up table for columns
var row_index=new Array(9);		// look-up table for rows
var solved;						// flag if solution found

var animthread=null;
var	animtrigger=0;
var spiral=new Array(0,1,2,3,4,5,6,7,8,17,26,35,44,53,62,71,80,79,78,77,76,75,74,73,72,63,54,45,36,27,18,9,10,11,12,13,14,15,16,25,34,43,52,61,70,69,68,67,66,65,64,55,46,37,28,19,20,21,22,23,24,33,42,51,60,59,58,57,56,47,38,29,30,31,32,41,50,49,48,39,40);
var target0=new Array(40,40);
var target1=new Array(30,31,32,41,50,49,48,39);
var target2=new Array(20,21,22,23,24,33,42,51,60,59,58,57,56,47,38,29);
var target3=new Array(10,11,12,13,14,15,16,25,34,43,52,61,70,69,68,67,66,65,64,55,46,37,28,19);
var target4=new Array(0,1,2,3,4,5,6,7,8,17,26,35,44,53,62,71,80,79,78,77,76,75,74,73,72,63,54,45,36,27,18,9);

// random number generator
var today=new Date();
var seed=today.getTime();
function rnd() {
	seed = (seed*9301+49297) % 233280;
	return seed/(233280.0);
};
function rand(number) {
	return Math.floor(rnd()*number);
};

// clear back to empty
function doclear()
{
	var i;

	for (i=0;i<81;i++) {
		var pfield=document.getElementById("c"+i);
		pfield.className="digit";
		pfield.style.backgroundColor="#CEE7FF";
		pfield.value=' ';
		board[i]=allow_mask | solve_mask | digit_mask;
	}
	solved=0;
}

// once only initialisation
function initialise()
{
	// initialise quick indexes
	box_index[0]=new Array(0,1,2,9,10,11,18,19,20);
	box_index[1]=new Array(3,4,5,12,13,14,21,22,23);
	box_index[2]=new Array(6,7,8,15,16,17,24,25,26);
	box_index[3]=new Array(27,28,29,36,37,38,45,46,47);
	box_index[4]=new Array(30,31,32,39,40,41,48,49,50);
	box_index[5]=new Array(33,34,35,42,43,44,51,52,53);
	box_index[6]=new Array(54,55,56,63,64,65,72,73,74);
	box_index[7]=new Array(57,58,59,66,67,68,75,76,77);
	box_index[8]=new Array(60,61,62,69,70,71,78,79,80);
	row_index[0]=new Array(0,1,2,3,4,5,6,7,8);
	row_index[1]=new Array(9,10,11,12,13,14,15,16,17);
	row_index[2]=new Array(18,19,20,21,22,23,24,25,26);
	row_index[3]=new Array(27,28,29,30,31,32,33,34,35);
	row_index[4]=new Array(36,37,38,39,40,41,42,43,44);
	row_index[5]=new Array(45,46,47,48,49,50,51,52,53);
	row_index[6]=new Array(54,55,56,57,58,59,60,61,62);
	row_index[7]=new Array(63,64,65,66,67,68,69,70,71);
	row_index[8]=new Array(72,73,74,75,76,77,78,79,80);
	col_index[0]=new Array(0,9,18,27,36,45,54,63,72);
	col_index[1]=new Array(1,10,19,28,37,46,55,64,73);
	col_index[2]=new Array(2,11,20,29,38,47,56,65,74);
	col_index[3]=new Array(3,12,21,30,39,48,57,66,75);
	col_index[4]=new Array(4,13,22,31,40,49,58,67,76);
	col_index[5]=new Array(5,14,23,32,41,50,59,68,77);
	col_index[6]=new Array(6,15,24,33,42,51,60,69,78);
	col_index[7]=new Array(7,16,25,34,43,52,61,70,79);
	col_index[8]=new Array(8,17,26,35,44,53,62,71,80);

	// clear board
	doclear();

	// restore from cookie
	restoreboard();

	// display cursor
	ccell=0;
	var pfield=document.getElementById("c"+ccell);
	if (board[ccell]&lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.style.backgroundColor="#CEE7FF";
	pfield.focus();

	// trap key presses
	document.onkeydown=kbdhandler;

}

// get row index from cell number
function getrow(cell)
{
	return(Math.floor(cell/9));
}

// get column from cell number
function getcol(cell)
{
	return(Math.floor(cell%9));
}

// get box from cell number
function getbox(cell)
{
	var row=getrow(cell);
	var col=getcol(cell);

	return(Math.floor(3*Math.floor(row/3)+Math.floor(col/3)));
}

// move cursor to cell
function cell(cc)
{
	var pfield=document.getElementById("c"+ccell);
	if (board[ccell]&lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.style.backgroundColor="#CEE7FF";
	ccell=cc;
	pfield=document.getElementById("c"+ccell);
	if (board[ccell]&lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.style.backgroundColor="#ccddee";
	pfield.focus();
}

// move hint highlight to cell
function cellblink(cc)
{
	var pfield=document.getElementById("c"+ccell);
	if (board[ccell]&lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.style.backgroundColor="#eeeeee";
	ccell=cc;
	var pfield=document.getElementById("c"+ccell);
	if (board[ccell]&lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.style.backgroundColor="#ccddee";
	pfield.focus();
}

// enter a digit from digit buttons
function dodigit(num)
{
	var pfield=document.getElementById("c"+ccell);
	if (checklegal(board,ccell,num)&&!(board[ccell]&lock_flag)) {
		pfield.value=digit[num];
		board[ccell] = (board[ccell] & ~digit_mask) | num;
		solved=0;
		if (animtrigger && checksolution()) {
			animthread=setInterval("animate()",60);
			setTimeout("noanimate()",20000);
			animtrigger=0;
		}
	}
	else if (!(board[ccell]&lock_flag)) {
		pfield.value=' ';
		board[ccell] |= digit_mask;
		solved=0;
		dobeep();
	}
	cell(ccell);
}

// enter a digit from keyboard
function kbdhandler(e)
{
	var pfield=document.getElementById("c"+ccell);

	if (!e) e=window.event;
	var chr = String.fromCharCode(e.keyCode);

	if (('1'<=chr)&&(chr <='9')) {
		var d=chr.charCodeAt(0)-49;
		dodigit(d);
	}
	else if (('a'<=chr)&&(chr <='i')) {
		var d=chr.charCodeAt(0)-97;
		dodigit(d);
	}
	else if ((chr==' ')||(e.keyCode==46)||(e.keyCode==8)) {
		if ((board[ccell]&lock_flag)==0) {
			pfield.value=' ';
			board[ccell] |= digit_mask;
			cell(ccell);
			solved=0;
		}
	}
	else if (chr=='\x25') {
		// left arrow
		var cc=ccell-1;
		if (cc<0) {
			cc += 81;
		}
		cell(cc);
	}
	else if (chr=='\x26') {
		// up arrow
		var cc=ccell-9;
		if (cc<0) {
			if (cc==-9)
				cc = 80;
			else
				cc += 80;
		}
		cell(cc);
	}
	else if (chr=='\x27') {
		// right arrow
		var cc=ccell+1;
		if (cc>80) {
			cc -= 81;
		}
		cell(cc);
	}
	else if (chr=='\x28') {
		// down arrow
		var cc=ccell+9;
		if (cc > 80) {
			if (cc==89)
				cc=0;
			else
				cc -= 80;
		}
		cell(cc);
	}
//	else if (chr==0)
//		alert("Got key code="+e.keyCode);
//	else
//		alert("Got key code="+e.keyCode+" char="+chr);
	pfield.focus();
}

// check user input is allowed
// note that we allow users to enter incorrect digits
// that happen to still be legal according to the rules
function checklegal(board,cc,d)
{
	var hold=board[cc];
	var i,j;
	board[cc] |= digit_mask;

	// check row
	var row=getrow(cc);
	for (j=0;j<9;j++)
		if ((board[row_index[row][j]]&digit_mask)==d) {
			board[cc]=hold;
			return(0);
		}

	// check column
	var col=getcol(cc);
	for (j=0;j<9;j++)
		if ((board[col_index[col][j]]&digit_mask)==d) {
			board[cc]=hold;
			return(0);
		}

	// check box
	var box=getbox(cc);
	for (j=0;j<9;j++)
		if ((board[box_index[box][j]]&digit_mask)==d) {
			board[cc]=hold;
			return(0);
		}

	// OK
	board[cc]=hold;
	return(1);
}

// lock the currently displayed digits
function dolock()
{
	var i;

	for (i=0;i<81;i++) {
		if ((board[i]&digit_mask)<9) {
			var pfield=document.getElementById("c"+i);
			pfield.className="digitlock";
			board[i] |= lock_flag;
		}
	}
}

// reset the board to the locked digits only
function doreset()
{
	var i;

	for (i=0;i<81;i++) {
		if (!(board[i]&lock_flag)) {
			var pfield=document.getElementById("c"+i);
			pfield.value=' ';
			board[i] |= digit_mask;
		}
	}
}

// play a warning beep
function dobeep() {
	var thissound=document.getElementById("beep");
	thissound.Play();
}

// check solution
function checksolution()
{
	var	i,sum;

	// check rows
	for (i=0;i<9;i++) {
		sum=0;
		for (j=0;j<9;j++) sum += board[row_index[i][j]] & digit_mask;
		if (sum!=36) return(0);
	}
	// check cols
	for (i=0;i<9;i++) {
		sum=0;
		for (j=0;j<9;j++) sum += board[col_index[i][j]] & digit_mask;
		if (sum!=36) return(0);
	}
	// check boxes
	for (i=0;i<9;i++) {
		sum=0;
		for (j=0;j<9;j++) sum += board[box_index[i][j]] & digit_mask;
		if (sum!=36) return(0);
	}
	return(1);
}

// set a digit into a board cell
function setdigit(cc,num)
{
	var pfield=document.getElementById("c"+cc);
	if (board[cc] & lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.value=digit[num];
	board[cc] = (board[cc] & ~digit_mask) | num;
}

// check the contents of all boxes
function boxcheck(board)
{
	var i,j,d,sum,last,last2,last3;

	for (i=0;i<9;i++) {
		for (d=0;d<9;d++) {
			sum=0;
			last=-1;
			last2=-1;
			last3=-1;
			for (j=0;j<9;j++) {
				if (board[box_index[i][j]]&allow_bits[d]) {
					sum++;
					last3=last2;
					last2=last;
					last=box_index[i][j];
				}
				else
					sum += ((board[box_index[i][j]] & solve_mask)==(d << 4)) ? 1: 0;
			}
			// if #possible is 0 then fail
			if (sum==0) return(0);
			// if #possible is 1 then fix it in solution
			if ((sum==1)&&(last>=0)) {
				if (!setallowed(board,last,d)) return(0);
			}
			// if #possible is 2 then if both on same row, can't be elsewhere on row
			if ((sum==2)&&(last>=0)&&(last2>=0)&&(getrow(last)==getrow(last2))) {
				for (j=0;j<9;j++) {
					var c=row_index[getrow(last)][j];
					if ((c!=last)&&(c!=last2)) {
						if (board[c]&allow_bits[d]) {
							board[c] &= ~allow_bits[d];
							if ((board[c]&allow_mask)==0) return(0);
						}
					}
				}
			}
			// if #possible is 2 then if both on same col, can't be elsewhere on col
			if ((sum==2)&&(last>=0)&&(last2>=0)&&(getcol(last)==getcol(last2))) {
				for (j=0;j<9;j++) {
					var c=col_index[getcol(last)][j];
					if ((c!=last)&&(c!=last2)) {
						if (board[c]&allow_bits[d]) {
							board[c] &= ~allow_bits[d];
							if ((board[c]&allow_mask)==0) return(0);
						}
					}
				}
			}
			// if #possible is 3 then if all on same row, can't be elsewhere on row
			if ((sum==3)&&(last>=0)&&(last2>=0)&&(last3>=0)&&(getrow(last)==getrow(last2))&&(getrow(last)==getrow(last3))) {
				for (j=0;j<9;j++) {
					c=row_index[getrow(last)][j];
					if ((c!=last)&&(c!=last2)&&(c!=last3)) {
						if (board[c]&allow_bits[d]) {
							board[c] &= ~allow_bits[d];
							if ((board[c]&allow_mask)==0) return(0);
						}
					}
				}
			}
			// if #possible is 3 then if all on same col, can't be elsewhere on col
			if ((sum==3)&&(last>=0)&&(last2>=0)&&(last3>=0)&&(getcol(last)==getcol(last2))&&(getcol(last)==getcol(last3))) {
				for (j=0;j<9;j++) {
					c=col_index[getcol(last)][j];
					if ((c!=last)&&(c!=last2)&&(c!=last3)) {
						if (board[c]&allow_bits[d]) {
							board[c] &= ~allow_bits[d];
							if ((board[c]&allow_mask)==0) return(0);
						}
					}
				}
			}
		}
	}
	return(1);
}

// check the contents of all rows
function rowcheck(board)
{
	var i,j,d,sum,last;

	for (i=0;i<9;i++) {
		for (d=0;d<9;d++) {
			sum=0;
			last=-1;
			for (j=0;j<9;j++) {
				if (board[row_index[i][j]]&allow_bits[d]) {
					sum++;
					last=j;
				}
				else
					sum += ((board[row_index[i][j]] & solve_mask)==(d << 4)) ? 1: 0;
			}
			if (sum==0) return(0);
			if ((sum==1)&&(last>=0)) {
				if (!setallowed(board,row_index[i][last],d)) return(0);
			}
		}
	}
	return(1);
}

// check the contents of all columns
function colcheck(board)
{
	var i,j,d,sum,last;

	for (i=0;i<9;i++) {
		for (d=0;d<9;d++) {
			sum=0;
			last=-1;
			for (j=0;j<9;j++) {
				if (board[col_index[i][j]]&allow_bits[d]) {
					sum++;
					last=j;
				}
				else
					sum += ((board[col_index[i][j]] & solve_mask)==(d << 4)) ? 1: 0;
			}
			if (sum==0) return(0);
			if ((sum==1)&&(last>=0)) {
				if (!setallowed(board,col_index[i][last],d)) return(0);
			}
		}
	}
	return(1);
}

// set a digit into a board, clearing allowed flags elsewhere
function setallowed(board,cc,num)
{
	var i,j,k,l,d;
	var s;

	// clear alternatives in this cell
	board[cc] &= ~allow_mask;
	// and set value as solution
	board[cc] = (board[cc] & ~solve_mask) | (num << 4);

	// clear this digit on same row
	var row=getrow(cc);
	for (j=0;j<9;j++) {
		if (board[row_index[row][j]]&allow_bits[num]) {
			board[row_index[row][j]] &= ~allow_bits[num];
			if ((board[row_index[row][j]]&allow_mask)==0) return(0);
		}
	}

	// clear this digit on same column
	var col=getcol(cc);
	for (j=0;j<9;j++) {
		if (board[col_index[col][j]]&allow_bits[num]) {
			board[col_index[col][j]] &= ~allow_bits[num];
			if ((board[col_index[col][j]]&allow_mask)==0) return(0);
		}
	}

	// clear this digit in same box
	var box=getbox(cc);
	for (j=0;j<9;j++) {
		if (board[box_index[box][j]]&allow_bits[num]) {
			board[box_index[box][j]] &= ~allow_bits[num];
			if ((board[box_index[box][j]]&allow_mask)==0) return(0);
		}
	}

	// process all singletons created by setting
	for (i=0;i<81;i++)
		for (d=0;d<9;d++)
			if ((board[i]&allow_mask)==allow_bits[d])
				if (!setallowed(board,i,d)) return(0);

	// check each digit still available in each box, row and column
	if (!boxcheck(board)||!rowcheck(board)||!colcheck(board))
		return(0);

	// process all singletons created by setting (double check)
	for (i=0;i<81;i++)
		for (d=0;d<9;d++)
			if ((board[i]&allow_mask)==allow_bits[d])
				if (!setallowed(board,i,d)) return(0);

	return(1);
}

// check if board is a solution
function chksolved(board)
{
	var i;
	var nchoices=0;

	// count # choices left
	for (i=0;i<81;i++)
		if ((board[i]&allow_mask)!=0)
				nchoices++;

	// solved?
	if (nchoices==0) solved=1;

	// OK
	return(solved);
}

// debug variable to test depth of search
var maxlevel;

// attempt to solve from this situation
function attempt(pboard,level)
{
	var board=new Array(81);
	var i,j,k;
	var s,e;

	// check for runaway
	if (level > maxlevel) {
		maxlevel=level;
		// alert("Level="+level);
	}
	if (level > 25) return;		// probably gone wrong

	// pick starting square at random
	i=s=rand(81);
	do {
	  if ((pboard[i]&allow_mask)!=0) {
		// pick starting digit at random
		j=e=rand(9);
		do {
		  if (pboard[i]&allow_bits[j]) {
			// push current solution
			for (k=0;k<81;k++) board[k]=pboard[k];
			// try out digit
			if (setallowed(board,i,j)) {
				board[i] = (board[i] & ~digit_mask) | j;
				if (chksolved(board)) {
					for (k=0;k<81;k++) pboard[k]=board[k];
					return;
				}
				// recurse
				attempt(board,level+1);
				if (chksolved(board)) {
					for (k=0;k<81;k++) pboard[k]=board[k];
					return;
				}
				// no good
				board[i] |= digit_mask;
				if (level > 2) return;	// don't both searching anymore
			}
		  }
		  j=(j+1)%9;
		} while (j!=e);
	  }
	  i=(i+1)%81;
	} while (i!=s);
}

// create a new initial configuration
function docreate()
{
	var i,d;

	do {
		// clear the board
		doclear();
		solved=0;
		maxlevel=0;

		// assign one of each digit at random
		for (d=0;d<9;d++) {
			i=rand(81);
			if (board[i]&allow_bits[d]) {
				setallowed(board,i,d);
				board[i] = (board[i] & ~digit_mask) | d;
			}
		}

		// attempt to solve from here
		attempt(board,0);

		// display result
		for (i=0;i<81;i++) {
			if ((0<=(board[i]&digit_mask))&&((board[i]&digit_mask) < 9)) board[i] |= lock_flag;
			setdigit(i,board[i]&digit_mask);
		}

		if (!solved)
			alert("Failed to make puzzle\nTrying again.");

	} while (!solved);

	// display cursor
	ccell=0;
	var pfield=document.getElementById("c"+ccell);
	if (board[ccell]&lock_flag)
		pfield.className="digitlock";
	else
		pfield.className="digit";
	pfield.style.backgroundColor="cornflowerbluec";
	pfield.focus();

	// set animation trigger
	animtrigger=1;
}

// find a possible move in a board
function findmove(board)
{
	var i,d;
	var s;

	// pick starting square at random
	i=s=rand(81);
	do {
		if (!(board[i]&allow_mask)) {
			d=(board[i]&solve_mask)>>4;
			if ((board[i]&digit_mask)!=d) return(i);
		}
		i=(i+1)%81;
	} while (i!=s);
	// failed
	return(-1);
}

// give a hint
function dohint()
{
	var tboard=new Array(81);
	var i,j,k,l,d;
	var s,t;

	// reset work arrays
	for (i=0;i<81;i++)
		tboard[i]=allow_mask | solve_mask | digit_mask;

	// add in current cells
	s=-1;
	i=t=rand(81);
	do {
		c=board[i] & digit_mask;
		if ((0<=c)&&(c<9)) {
			tboard[i] = (tboard[i] & ~digit_mask) | c;
			if (!setallowed(tboard,i,c)) {
				alert("Starting position impossible, lastchar="+digit[c]);
				return;
			}
			if ((s=findmove(tboard))>=0) {
				if ((board[s]&digit_mask)==digit_mask) break;
			}
		}
		i=(i+1)%81;
	} while (i!=t);

	// find a possible go
	// s=findmove(tboard);

	if (s>=0) {
		cellblink(s);
	}
	else {
//		for (i=0;i<81;i++) {
//			s="";
//			for (j=0;j<9;j++) if (tboard[i]&allow_bits[j]) s=digit[j]+s;
//			if (s!="") {
//				var pfield=document.getElementById("c"+i);
//				pfield.value="("+s+")";
//			}
//		}
		alert("No hint available.");
		cell(ccell);
	}
}

// find and display complete solution
function dosolution(show)
{
	var pboard=new Array(81);
	var	i,c;

	if (show) {

		if (!solved) {
			// reset solution
			for (i=0;i<81;i++) pboard[i] = allow_mask | solve_mask | digit_mask;
			// add in current cells
			for (i=0;i<81;i++) {
				c=board[i] & digit_mask;
				if ((0<=c)&&(c<9)) {
					if (!setallowed(pboard,i,c)) {
						alert("Starting position impossible.\nFailed at cell="+i+" char="+digit[c]);
						return;
					}
				}
			}
			// attempt solution
			attempt(pboard,0);

			// copy solution into main board
			for (i=0;i<81;i++)
				board[i] = (board[i] & ~solve_mask) | (pboard[i] & solve_mask);
		}

		// display solution
		for (i=0;i<81;i++) {
			var pfield=document.getElementById("c"+i);
			pfield.value=digit[(board[i]&solve_mask)>>4];
		}
	}
	else {
		// restore board contents
		for (i=0;i<81;i++) {
			var pfield=document.getElementById("c"+i);
			pfield.value=digit[board[i]&digit_mask];
		}
	}
}

// save board to cookie on user's machine
function saveboard()
{
	var s=board.join("|");
	var exp = new Date();
	var oneYearFromNow = exp.getTime() + (365 * 24 * 60 * 60 * 1000);
	exp.setTime(oneYearFromNow);
	document.cookie = "sudoku="+s+"; expires=" + exp.toGMTString();
}

// get a variable from a cookie string
function getCookieData(labelName)
{
	var labelLen = labelName.length;
	var cookieData = document.cookie;
	var cLen = cookieData.length;
	var i = 0;
	var cEnd;
	while (i < cLen) {
		var j = i + labelLen;
		if (cookieData.substring(i,j) == labelName) {
			cEnd = cookieData.indexOf(";",j);
			if (cEnd == -1) {
				cEnd = cookieData.length;
			}
			return unescape(cookieData.substring(j+1, cEnd));
		}
		i++;
	}
	return "";
}

// restore board from cookie on user's machine
function restoreboard()
{
	var s=getCookieData("sudoku");
	var a=s.split("|");
	if (a.length==81) {
		var i;
		for (i=0;i<81;i++) {
			board[i]=a[i];
			setdigit(i,board[i]&digit_mask);
		}
	}
}

// animation state
var state=0;

// animate a pattern of colours
function animate()
{
	var	i,j;
	var	colours=new Array("#ffffcc", "#ffccff","#ccffff","#eeeeee");

	if (state < 81) {
		i=spiral[(state+80)%81];
		j=spiral[state];
		var pfield=document.getElementById("c"+i);
		pfield.style.backgroundColor="#eeeeee";
		var pfield=document.getElementById("c"+j);
		pfield.style.backgroundColor="#eecccc";
		var pfield=document.getElementById("c"+(80-i));
		pfield.style.backgroundColor="#eeeeee";
		var pfield=document.getElementById("c"+(80-j));
		pfield.style.backgroundColor="#cceecc";
	}
	else {
		clearInterval(animthread);
		animthread=setInterval("animate()",100);
		for (i=0;i<target0.length;i++) {
			j=target0[i];
			var pfield=document.getElementById("c"+j);
			pfield.style.backgroundColor=colours[state%4];
		}
		for (i=0;i<target1.length;i++) {
			j=target1[i];
			var pfield=document.getElementById("c"+j);
			pfield.style.backgroundColor=colours[(state+1)%4];
		}
		for (i=0;i<target2.length;i++) {
			j=target2[i];
			var pfield=document.getElementById("c"+j);
			pfield.style.backgroundColor=colours[(state+2)%4];
		}
		for (i=0;i<target3.length;i++) {
			j=target3[i];
			var pfield=document.getElementById("c"+j);
			pfield.style.backgroundColor=colours[(state+3)%4];
		}
		for (i=0;i<target4.length;i++) {
			j=target4[i];
			var pfield=document.getElementById("c"+j);
			pfield.style.backgroundColor=colours[(state+4)%4];
		}
	}

	state = state+1;
}

// cancel animation
function noanimate()
{
	if (animthread) {
		clearInterval(animthread);
		animthread=null;
	}
	for (i=0;i<81;i++) {
		var pfield=document.getElementById("c"+i);
		pfield.style.backgroundColor="#eeeeee";
		pfield.className="digit";
	}
	state=0;
}

</script>



<center>

<b>Uitleg</b><BR><BR>
Vul het Diagram op een zodanig manier in dat alle cijfers van 1 tot en met 9 slechts één keer voorkomen in alle horizontale rijen en verticale kolommen, en dat alle cijfers van 1 tot en met 9 voorkomen in elk van de negen vierkantjes van 3 x 3 vakjes.
<BR><BR>
Klik op "Create" om een nieuwe speelveld te maken. Als je een cijfer wilt toevoegen op het speelveld, klik dan op het desbetreffende vakje en klik op het cijfer. Wil je het cijfer weer weghalen, klik dan op het streepje (onder de 9).
<BR><BR>
Klik op Clear om alles van het veld weg te halen, ook de begincijfers.<BR><BR>
ALs je een cijfer wilt vastleggen, zodat je deze niet per ongeluk weer weg kan halen, dan klik je het vakje aan waar het cijfer in staat en dan klik je op Lock. Je ziet het cijfer van kleur veranderen.<BR><BR>
Wil je het speelveld overnieuw spelen, dan kan je op reset drukken.<BR><BR>

Als je op "hint" klikt, dan wordt een vakje geselecteerd waar je al makkelijk een cijfer in kan vullen.<BR><BR>
En als laatste "solve", als je hier op klikt en je houdt je muisknop ingedrukt, dan zie je het gehele speelveld ingevuld!
<BR><BR>
Ik wens iedereen veel succes!





</html>