Acorn User 10/AU_CD10.iso/Archived/Internet/jvscript116beta/JvScript/!JvScript/Resources/Scripts/Games/5

Text File | 1999-09-15 | 6.7 KB | 248 lines

#newformat
_title:Towers Of Hanoi
_author:TJS
_description:Towers of Hanoi in JavaScript. (Requires v1.1)

_url:URL of images directory

_insert-in:inbody
<SCRIPT LANGUAGE="JavaScript1.1" TYPE="text/javascript">
<!--
// Towers of Hanoi

// Preload images
function preload() {
  this.length = preload.arguments.length;
  for (var i = 0; i < this.length; i++) {
    this[i] = new Image();
    this[i].src = "¤url_object$(1)¤" + preload.arguments[i];
  }
}

var pics = new preload("disk1.gif","disk2.gif",
  "disk3.gif","disk4.gif","disk5.gif","disk6.gif",
  "disk7.gif","post.gif", "disk1h.gif","disk2h.gif",
  "disk3h.gif","disk4h.gif","disk5h.gif","disk6h.gif",
  "disk7h.gif","posttop.gif");

// Variables
var selectedr = null;
var selectedc = null;
var maxposts = 3;
var maxdisks = 7;
var all_posts = 3;
var startpost = 1;
var endpost = (startpost-1 < 0 ? maxposts-1 : startpost-1);
var disks = 7;
var imgwidth = 160;
var imgheight = 14;
var game_is_over = false;
var board = new Array(maxposts);
board[0] = new Array(maxdisks + 1);
board[1] = new Array(maxdisks + 1);
board[2] = new Array(maxdisks + 1);

function initboard(startpost, disks) {
  var len = board[0].length;
  selectedc = null;
  selectedr = null;
  game_is_over = false;
  endpost = (startpost-1 < 0 ? maxposts-1 : startpost-1);

  for (i = 0; i < len; i++) {
    board[0][i] = 0;
    board[1][i] = 0;
    board[2][i] = 0;
  }
  for (i = len-disks, j = 0; i < len; i++, j++) {
    board[startpost][i] = len - j - 1;
  }
}

function drawall() {
  for (j=0; j<board.length; j++) {
    for (i=0; i<board[j].length; i++) {
      draw(j,i, getName( board[j][i]));
    }
  }
  message("You may begin! Select a piece to move.");
}

// restart the game
function restart(start) {
  startpost = start;
  disks = document.forms[0].disc.options[document.forms[0].disc.selectedIndex].text;
  initboard(startpost,disks);
  drawall();
}
// Initialize board
initboard(startpost, disks);


// Helper functions
// generate the name of the image for .src
function getName( num ) {
  if (num == 0) return "post.gif";
  return "disk" + num + ".gif";
}

// put message in message box
function message(str) {
 if (!game_is_over)
  document.disp.message.value = str;
}

// is the post empty?
function isempty(num) {
  for (i = 0; i < board[num].length; i++) {
    if ( board[num][i] != 0) return false;
  }
  return true;
}

// return the topmost disk of the post
function topmost(num) {
  for (i = 0; i < board[num].length; i++) {
    if (board[num][i] != 0) return  i;
  }
  return -1;
}

// is the click on a post element?
function ispost(i,j) {
  return (board[j][i] == 0);
}

// is click on the top disk?
function istopdisk(i,j) {
  return (board[j][i-1] == 0);
}

// draw the board
function drawboard() {
  document.writeln("<CENTER><h2>The Towers of Hanoi</h2><p>");
  document.writeln("<table cellspacing=0 cellpadding=0 border=0>");
  document.write("<tr>");
  for (j = 0; j < board.length; j++) {
    document.write("<td>");
    document.write("<a href='javascript:clicked("+0+","+j+")'><img src='http://javascript.internet.com/img/hanoi/posttop.gif' border=0></a><br>");
    for (i=0; i< board[0].length; i++) {
      document.write("<a href='javascript:clicked("+i+","+j+")'>");
      document.write("<img src='http://javascript.internet.com/img/hanoi/" + getName(board[j][i]) + "' name='pos"+ j + i + "' border=0><br>");
      document.write("</a>");
    }
    document.writeln("</td>");
  }
  document.write("</tr></table>");
  document.write("<form name='disp'><textarea name='message' wrap=virtual rows=2 cols=40></textarea><br>" +
    "Disks: <select name=\"disc\" size=1><option>3<option>4<option>5<option>6<option selected>7</select><input "
    +"type=button value=\"Start the Game Over\" onClick=\"restart(startpost);\"><input "
    +"type=button value=\"Solve It!\" onClick=\"restart(startpost);setTimeout('hanoi(disks,startpost,endpost)',400)\"></form>");
}

// draw image "name" at position "x,y"
function draw(x,y,name) {
  document.images["pos"+x+""+y].src = "http://javascript.internet.com/img/hanoi/" + name;
}

// process the click
function clicked(i,j) {
  document.forms[0].message.focus(); // get rid of annoying outline in MSIE

  if (game_is_over)  restart(startpost = endpost);
  if (!isselection() && ispost(i,j)) { message("Select a piece to move."); return; }
  if (!ispost(i,j)) { toggle(j); return; };
  if (ispost(i,j) && selectedc == j) { message("Move the piece to a different post."); return; }
  if (!legalmove(j)) { message("That is not a legal move. Try again."); return; }
  move(j); return;
}

// is the move legal?
function legalmove(j) {
  // is legal if empty
  if (isempty(j)) return true;
  return (board[j][topmost(j)] < board[selectedc][selectedr]);
}

// is there a piece selected?
function isselection() {
  return selectedc != null;
}

// select/deselect the topmost piece on the post
function toggle( num ) {
  // find the topmost piece
  var toppos = topmost(num);

  // toggle off if same column
  if (selectedc == num && selectedr == toppos) {
    selectedc = null; selectedr = null;
    draw(num,toppos,"disk" + board[num][toppos] + ".gif");
    message("Select a piece to move.");
    return;
  }
  // delselect the current selection
  if (isselection()) {
    draw(selectedc,selectedr,"disk" + board[selectedc][selectedr] + ".gif");
  }
  // make new selection
  selectedc = num; selectedr = toppos;
  draw(num,toppos,"disk" + board[num][toppos] + "h.gif");
  message("Click on the post to which you want to move the disk.");
}

// move the disk to this post
function move( num ) {
  // find the topmost piece
  var toppos = (!isempty(num) ? topmost(num) : board[num].length);
  board[num][toppos-1] = board[selectedc][selectedr];
  board[selectedc][selectedr] = 0;
  draw(selectedc,selectedr,"post.gif");
  draw(num,toppos-1,"disk" + board[num][toppos-1] + ".gif");
  selectedc = null; selectedr = null;
  message("Select a piece to move.");
  game_over();
}

// solve the puzzle
function hanoi(no_of_disks, start_post, goal_post) {
  if (no_of_disks > 0) {
    var free_post = all_posts - start_post - goal_post;
    hanoi (no_of_disks - 1, start_post, free_post);
    toggle(start_post);
    delay(1000);
    move(goal_post);
    delay(1000);
    hanoi (no_of_disks - 1 , free_post, goal_post);
  }
}

// slow things down
function delay(num) {
  for (i = 0; i < num; i++) ;
}

// returns true of the game is over
function game_over() {
  var filledpost = null;
  var val = 0;
  for (k = 0; k < board.length; k++)  {
    val += ( isempty(k) ? 1 : 0 );
    if (!isempty(k)) filledpost = k;
  }

  if (val == 2 && isempty(startpost)) {
    message("You won!");
    game_is_over = true;
    endpost = filledpost;
  }
  return game_is_over;
}


drawboard();
message("You may begin! Select a piece to move.");

// -->
</SCRIPT>
_end-insert: