抽奖概率

最新推荐文章于 2023-08-14 13:46:51 发布

转载最新推荐文章于 2023-08-14 13:46:51 发布 · 503 阅读

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<!doctype html>
<html>
<head lang="zh">
    <meta charset="utf-8">
    <title>灵域</title>
    <meta name="renderer" content="webkit">
<body>
<input type="button" value="10000" id="input1">
<h1>一等奖:5‰,二等奖:3%,三等奖:80%,纪念奖(谢谢惠顾)</h1>
<ul>
	<li>一等奖 : <span></span></li>
    <li>二等奖 : <span></span></li>
    <li>三等奖 : <span></span></li>
    <li>纪念奖 : <span></span></li>
</ul>
<script>
var oInput = document.getElementById('input1');
var aSpan = document.getElementsByTagName('span');
var size = 1000;
var arr1 = [0.005*size , 0.03*size , 0.8 * size];
var arr2 = [];
var num = 0;
oInput.onclick = function(){
	arr2=[];
	num = 0
	for(var i =0; i< arr1.length; i++){
		var iNow = 0;
		num += arr1[i];
		arr2.push({iNow:0,val:num})
	}
	var fre = parseInt(oInput.value);
	var sum = 0;
	for(var i=0; i< fre; i++){
		var val = Math.random()*size;
		fnCount(val);

	}

	for(var i=0;i<aSpan.length;i++){
		//没中奖的，将前面的累加
		if(aSpan.length-1 == i){
			aSpan[i].innerHTML = fre - sum;
		}
		//中奖的
		else{
			aSpan[i].innerHTML = arr2[i].iNow;
			sum += arr2[i].iNow;
		}
	}
}

function fnCount(val){
	for(var i=0;i<arr2.length;i++){
		if(arr2[i].val > val){
			arr2[i].iNow++;
			break;
		}
	}
}
</script>
</body>
</html>