要求，用户随意输入一个0~100的数，用二分法算出要多少次才能找到这个数
<!DOCTYPE html>
<html>
<head>
<title> ... </title>
<meta charset="utf-8"/>
<meta name="HSW" content="">
<meta name="Keywords" content="">
<style>
div[class*="3"]{
color:red;
}
</style>
</head>
<body>
<button id="button">按钮</button>
<p>niho</p>
<script>
var btn = document.getElementById("button");
btn.onclick = function(){
var num = parseInt(prompt('请输入一个数：'));
var high = 100,low = 0,half = 100;
(num!=high) && (half = parseInt((high-low)/2));
var n = 1;
while(half!=num){
if(half>num){
high = half;
half = low+parseInt((high-low)/2);
n++;
}else if(half<num){
low = half;
half += parseInt((high-low)/2);
n++;
}
}
console.log("共需要"+n+"次算出");
}
</script>
</body>
</html>