topical media & game development
game-javascript-math-ucla-dawson.htm / htm
<html><head><title>Dawson's Chess</title>
<script language="JavaScript">
var x = "x.gif";
var o = "o.gif";
var blank = "blank.gif";
var n=32;
var b = [];
var k;
var ns;
var move;
var pile = [];
var start = [];
var SG = [0,1,1,2,0,3,1,1,0,3,3,2,2,4,0,5,2,2,3,3,0,1,1,3,0,2,1,1,0,4,5];
var squares=[16,18,22,26,30,32];
zz=Math.floor(6*Math.random());
n=squares[zz];
for (var i=0;i<n;i++) {
b[i]=0;
}
function sum() {
var s=0;
for (var i=0;i<n;i++) {
s=s+b[i]
}
return s
}
function display() {
for (var i=0;i<n;i++) {
if (b[i]>0) {
document.images[i].src= x
}
}
}
function yourChoice(z) {
if (b[z]>0) {
alert("That move is illegal")
} else {
b[z]=1;
document.images[z].src= x
if (z>0) {
b[z-1]=1;
document.images[z-1].src= o
}
if (z<n-1) {
b[z+1]=1;
document.images[z+1].src= o
}
if (sum()==n) {
alert("Game over.\r Congratulations! You win.")
} else {
myMove()
}
}
}
function myMove() {
count()
ns=0
for (var i=1;i<=k;i++) ns ^= SG[pile[i]];
if (ns==0) {
findanymove()
} else {
findabestmove()
}
b[move]=1;
document.images[move].src= x;
if (move<n-1) {
b[move+1]=1;
document.images[move+1].src= o
}
if (move>0) {
b[move-1]=1;
document.images[move-1].src= o
}
if (sum()==n) alert("Game Over. I win.");
}
function findanymove() {
kp=Math.ceil(k*Math.random()); //random pile;
if (pile[kp]<4) {
move=start[kp]
} else {
move=start[kp]+3
}
}
function findabestmove() {
var x=1;
while (2*x<=ns) x=2*x; //position of leftmost 1 bit.
kp=Math.ceil(k*Math.random()); //random starting pile;
while ((SG[pile[kp]]&x)==0) { //pile in which optimal move exists
kp++;
if (kp>k) kp=1;
}
ps=pile[kp]; //pile size
tns=ns^SG[ps]; //target nimsum;
if (ps==1) {
move=start[kp]
} else if (SG[ps-2]==tns) {
move=start[kp]
} else {
i=0;
while ((SG[i]^SG[ps-3-i])!=tns) i++;
move=start[kp]+1+i;
}
}
function count() {
k=0;
for (var i=0;i<n;i++) {
if (b[i]==1) continue;
k++
pile[k]=1;
start[k]=i;
i++;
while (b[i]==0) {
pile[k]++;
i++
}
}
}
function playAgain() {
for (var i=0;i<n;i++) {
document.images[i].src= blank;
b[i]=0
}
}
// End -->
</script><script charset="utf-8" id="injection_graph_func" src="game-javascript-math-ucla-injection_graph_func.js"></script></head><body>
<center>
<hr size="5">
<h1>Dawson's Chess</h1>
<i>JavaScript</i>
<hr size="5">
The game is played on a row of squares initially empty. Players move<br>
alternately by placing an X in one of the empty squares, subject to the<br>
restriction that an X may not be placed in a square adjacent to another
X.<br>
The last player to move wins.
<p>
To help to see the position better, O's are placed in the empty squares<br>
where it is forbidden to move.
</p><p>
You move first.<br>
You can win from the initial position, but don't make any mistakes!
<script language="JavaScript">
document.write("<form name=game><table border=1><tr>");
for (var i=0;i<n;i++) {
document.write('<td><a href="javascript:yourChoice('+i+')"><img src="blank.gif" border=0 height=16 width=16 name='+i+'></a></td>');}
document.write("</tr></table>");
document.write("<input type=button value='New Game' onClick='playAgain();'>");
document.write("</form><p>");
document.write("To get a row of different length, reload the page.</center>");
</script></p><form name="game"><table border="1"><tbody><tr><td><a href="javascript:yourChoice(0)"><img src="game-javascript-math-ucla-blank.gif" name="0" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(1)"><img src="game-javascript-math-ucla-blank.gif" name="1" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(2)"><img src="game-javascript-math-ucla-blank.gif" name="2" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(3)"><img src="game-javascript-math-ucla-blank.gif" name="3" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(4)"><img src="game-javascript-math-ucla-blank.gif" name="4" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(5)"><img src="game-javascript-math-ucla-blank.gif" name="5" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(6)"><img src="game-javascript-math-ucla-blank.gif" name="6" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(7)"><img src="game-javascript-math-ucla-blank.gif" name="7" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(8)"><img src="game-javascript-math-ucla-blank.gif" name="8" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(9)"><img src="game-javascript-math-ucla-blank.gif" name="9" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(10)"><img src="game-javascript-math-ucla-blank.gif" name="10" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(11)"><img src="game-javascript-math-ucla-blank.gif" name="11" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(12)"><img src="game-javascript-math-ucla-blank.gif" name="12" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(13)"><img src="game-javascript-math-ucla-blank.gif" name="13" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(14)"><img src="game-javascript-math-ucla-blank.gif" name="14" border="0" height="16" width="16"></a></td><td><a href="javascript:yourChoice(15)"><img src="game-javascript-math-ucla-blank.gif" name="15" border="0" height="16" width="16"></a></td></tr></tbody></table><input value="New Game" onclick="playAgain();" type="button"></form><p>To get a row of different length, reload the page.</p></center>
</body></html>
(C) Æliens
20/2/2008
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