<SCRIPT LANGUAGE="LiveScript"> <!---Copyright 1996 Chris Englmeier <!---Feel free to use this script as long as these copyright <!-- line remain as is <!-- step = 0; diff=3; // change board when button is clicked function clear_all(form) { step = 0; for (i=0;i<9; ++i) { position="a"+i; form[position].value=""; } } // change board when button is clicked function clickit(field) { if (step == -1) {alert("Reset to play again"); return;} position=field.name.substring(1,2,1); position = 'a'+position; if (field.form[position].value !="") {alert("Can't go there"); return;} field.form[position].value="X"; if (eval_pos(field.form)) { field.form.output.value="You Win!"; step = -1; return; } position=get_move(field.form); field.form.output.value='I moved to ' + position.substring(1,2,1); if (position=="") { field.form.output.value="No Winner."; step = -1; return; } field.form[position].value="O"; if (eval_pos(field.form)) { field.form.output.value="You Lose!"; step = -1; } } // see if there is a winner function eval_pos(form) { if ((form.a0.value!="" && form.a0.value==form.a3.value && form.a0.value==form.a6.value)|| (form.a0.value!="" && form.a0.value==form.a1.value && form.a0.value==form.a2.value) || (form.a0.value!="" && form.a0.value==form.a4.value && form.a0.value==form.a8.value) || (form.a1.value!="" && form.a1.value==form.a4.value && form.a1.value==form.a7.value) || (form.a2.value!="" && form.a2.value==form.a5.value && form.a2.value==form.a8.value) || (form.a2.value!="" && form.a2.value==form.a4.value && form.a2.value==form.a6.value) || (form.a3.value!="" && form.a3.value==form.a4.value && form.a3.value==form.a5.value) || (form.a6.value!="" && form.a6.value==form.a7.value && form.a6.value==form.a8.value)) return true; else return false; } function f(a) { if (a == "") return "."; else return a; } // get position for move. function comp_move(form,player,weight,depth) { var cost; var bestcost=-2; var position; var newplayer; if (player=="X") newplayer="O"; else newplayer="X"; if (depth==diff) return 0; if (eval_pos(form)) return 1; for (var i=0; i<9; ++i) { position='a'+i; if (form[position].value != "") continue; form[position].value=player; cost = comp_move(form,newplayer, -weight, depth+1); if (cost > bestcost) { bestcost=cost; if (cost==1) i=9; } form[position].value=""; } if (bestcost==-2) bestcost=0; return(-bestcost); } // get position for move. function get_move(form) { var cost; var bestcost=-2; bestmove=""; // don't think about first move. if (step++ == 0) if (form.a4.value=="") return "a4"; else if (form.a0.value=="") return "a0"; for (var i=0; i<9; ++i) { localposition='a'+i; if (form[localposition].value != "") continue; form[localposition].value="O"; cost=comp_move(form,"X", -1, 0); if (cost > bestcost) { if (cost==1) i=9; bestmove=localposition; bestcost=cost; } form[localposition].value=""; } return bestmove; } // complain if user attempts to change board function complain(field) { field.form.output.focus(); // put focus eleswhere alert("Don't change the game fields directly!"); } //a href="http://www.ucsd.edu/ // the end --> </SCRIPT> <FORM> <INPUT SIZE=1 NAME="a0" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b0" OnClick="clickit(this)"> <INPUT SIZE=1 NAME="a1" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b1" OnClick="clickit(this)"> <INPUT SIZE=1 NAME="a2" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b2" OnClick="clickit(this)"><BR> <INPUT SIZE=1 NAME="a3" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b3" OnClick="clickit(this)"> <INPUT SIZE=1 NAME="a4" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b4" OnClick="clickit(this)"> <INPUT SIZE=1 NAME="a5" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b5" OnClick="clickit(this)"><BR> <INPUT SIZE=1 NAME="a6" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b6" OnClick="clickit(this)"> <INPUT SIZE=1 NAME="a7" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b7" OnClick="clickit(this)"> <INPUT SIZE=1 NAME="a8" OnFocus="complain(this)"> <INPUT TYPE="button" NAME="b8" OnClick="clickit(this)"><BR> <table border=0><tr><td> Message:</td><td> <INPUT NAME="output" TYPE="text"></td></tr> <tr><td>Difficulty: </td><td><SELECT NAME="difficulty" OnChange="diff=form.difficulty[form.difficulty.selectedIndex].value;"> <OPTION VALUE=1> Very Easy <OPTION VALUE=2> Easy <OPTION VALUE=3 SELECTED> Medium <OPTION VALUE=4> Hard (may think a long time) </SELECT></td></tr> <tr><td></td><td><INPUT TYPE="button" VALUE="Computer Moves First" OnClick="if (!step++) this.form.a4.value='O';"></td></tr> <tr><td></td> <td><INPUT TYPE="reset" VALUE="Restart" OnClick="clear_all(this.form)"></td></tr> </table> </FORM>