var numImagesToDisplay = 6;
var numLaImages = 24;
var numTwImages = 16;

var imageList = "";
var dirName = "";
if (Math.random() > 0.5) {// louisiana images	
  imageList = "la1.jpg";
  dirName = "louisiana";
  for (var i = 2; i <= numLaImages; i++) imageList = imageList + "," + "la" + i + ".jpg";
} else {// taiwan images   
  imageList = "tw1.jpg";
  dirName = "taiwan";
  for (var i = 2; i <= numTwImages; i++) imageList = imageList + "," + "tw" + i + ".jpg";
}


for (var i = 0; i < numImagesToDisplay; i++) {
  var itemName = getRandomListItem(imageList);
  document.write('<img src="images/' + dirName + '/' + itemName + '" border="0" width="120" height="90" />'); 
  imageList = listDeleteItem(imageList, itemName);
}


function getRandomListItem(strList) {
  if (strList == "") return "";
  var arrayItems = listToArray(strList);
  var rnd = Math.floor(Math.random() * arrayItems.length);
  if (rnd == arrayItems.length) rnd = rnd - 1;
  return arrayItems[rnd];  
}

function listDeleteItem(strList, itemName) {
  if (strList == itemName || strList == "") return ""; // strList has only one item or nothing
  var newStrList = "";
  var arrayItems = listToArray(strList);
  for (var i = 0; i < arrayItems.length; i++) {
    if (arrayItems[i] != itemName) {
      if (newStrList == "") newStrList = arrayItems[i];
	  else newStrList = newStrList + "," + arrayItems[i];
	}
  }
  return newStrList;
}

function listToArray(strList) {
  if (strList == "") return null;
  
  var numCommas = 0;
  var arrayCommaIndexes = new Array();
  var arrayItems = new Array();  
  
  for (var i = 0; i < strList.length; i++) {
    if (strList.charAt(i) == ",") {	  
	  numCommas++;
	  arrayCommaIndexes[numCommas-1] = i;
	  if (numCommas == 1) {
		arrayItems[numCommas-1] = strList.substring(0, i);
	  } else {
		arrayItems[numCommas-1] = strList.substring(arrayCommaIndexes[numCommas-2] + 1, arrayCommaIndexes[numCommas-1]);
	  }
	}
  }
  if (numCommas == 0) {
    arrayItems[0] = strList;
	return arrayItems;
  } else {
    arrayItems[numCommas] = strList.substring(arrayCommaIndexes[numCommas-1] + 1, strList.length);  
  }
  return arrayItems;  
}