/**
 * 输出随机广告
 * Author: y
 * Create At: 2009-3-26
 */

/********************************用户自定义********************************/
//定义广告对象，有N个广告就定义N个对象
var ad0 = {
    path: "http://image.lvdodo.com/www/090302/demo1.jpg",
    url: "http://www.lvdodo.com/christmas.htm",
    weights: 100
};

var ad1 = {
    path: "http://image.lvdodo.com/www/090302/demo24.jpg",
    url: "http://item.taobao.com/auction/item_detail.jhtml?x_id=0db1&item_id=a86f12cbbb2d33ffb0eedbd6cc3171df",
    weights: 1
};

var ad2 = {
    path: "http://image.lvdodo.com/www/090302/demo25.jpg",
    url: "http://item.taobao.com/auction/item_detail.jhtml?x_id=0db1&item_id=f563c9b1913c75b422d8e4f2e24f2589",
    weights: 1
};

var ad3 = {
    path: "http://image.lvdodo.com/www/090302/demo23.jpg",
    url: "http://www.lvdodo.com/products/whitening/752.aspx",
    weights: 1
};

//把广告对象加入数组
var adArr = new Array();
adArr.push(ad0);
adArr.push(ad1);
adArr.push(ad2);
adArr.push(ad3);
/********************************用户自定义 End********************************/

//按ad对象的weights值在adArr数组里从小到大排序(冒泡法)
var tem;
for (var m = 0; m < adArr.length; m++) {
    for (var n = m, k = n+1; k < adArr.length;  k++){
        if (adArr[n].weights > adArr[k].weights) {
            tem = adArr[n];
            adArr[n] = adArr[k];
            adArr[k] = tem;
        }
    }
}

//得到各个广告对象权值总和
var weightsSum = 0;
for (var i = 0; i < adArr.length; i++) {
    weightsSum += adArr[i].weights;
}

//得到一个随机数，并根据随机数确定某广告对象
var ad;
var rad = parseInt(Math.random() * weightsSum);
var min = 0, max = 0;
for (var j = 0; j < adArr.length; j++) {
    max = min + adArr[j].weights;
    if ((rad >= min) && (rad < max)) {
        ad = adArr[j];
        break;
    }
    min = max;
}

//把权值最大的作为输出
document.write("<a href=\"" + ad.url + "\" target=\"_blank\">");
document.write("<img src=\"" + ad.path + "\" border=\"0\"/>");
document.write("</a>");