求概率

java1618 2008-09-11 12:03:08

1出现的概率是20%，2出现的概率是30%，3出现的概率是10%，4出现的概率是40%，然后这几个数字出现的概率加起来是100%，也就是说没次一定会有一个数字出现，（只出现一个）该怎么写啊，请高手帮忙，急求原码！

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wdx2008 2008-09-18

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赫赫

zl_c 2008-09-12

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测试10000条记录

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />

<title>无标题文档</title>

</head>



<body onload="test(10000)">

<script language="javascript">

function getNum()

{

	var nArr = new Array(1,1,2,2,2,3,4,4,4,4);//按比例设置数组

	var i = Math.round(Math.random() * 9)	//随机产生下标

	return nArr[i];	//返回数值

}



function test(n)

{

	var span = document.getElementById("test");

	var temp = "";

	var tempArr = new Array(0,0,0,0);

	var tempN;

	for(var i = 0;i < n;i++) 

	{

		tempN = getNum();

		tempArr[tempN - 1]++;

		temp += String(tempN);

	}

	temp += "<br><br>1=" + tempArr[0] + "个 " + tempArr[0] / n * 100 + "%<br>"

	temp += "2=" + tempArr[1] + "个 " + tempArr[1] / n * 100 + "%<br>"

	temp += "3=" + tempArr[2] + "个 " + tempArr[2] / n * 100 + "%<br>"

	temp += "4=" + tempArr[3] + "个 " + tempArr[3] / n* 100  + "%"

	span.innerHTML = temp;

}

</script>

<span id="test"></span>

</body>

</html>

zl_c 2008-09-12

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<script language="javascript">

function getNum()

{

	var nArr = new Array(1,1,2,2,2,3,4,4,4,4);//按比例设置数组

	var i = Math.round(Math.random() * 9)	//随机产生下标

	return nArr[i];	//返回数值

}



function test(n)

{

	var span = document.getElementById("test");

	var temp = "";

	var tempArr = new Array(0,0,0,0);

	var tempN;

	for(var i = 0;i < n;i++) 

	{

		tempN = getNum();

		tempArr[tempN - 1]++;

		temp += String(tempN);

	}

	temp += "<br><br>1=" + tempArr[0] + "个 " + tempArr[0] / n * 100 + "%<br>"

	temp += "2=" + tempArr[1] + "个 " + tempArr[1] / n * 100 + "%<br>"

	temp += "3=" + tempArr[2] + "个 " + tempArr[2] / n * 100 + "%<br>"

	temp += "4=" + tempArr[3] + "个 " + tempArr[3] / n* 100  + "%"

	span.innerHTML = temp;

}

</script>

<span id="test"></span>

zl_c 2008-09-12

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<script language="javascript">

function getNum()

{

	var nArr = new Array(1,1,2,2,2,3,4,4,4,4);//按比例设置数组

	var i = Math.round(Math.random() * 9)	//随机产生下标

	return nArr[i];	//返回数值

}



getNum();	//调用示例

</script>