创建一个HTML页面，该页面接受用户在文本字段中的输入，作为非重复整数，长度为3个数字。当用户按下“显示”按钮时，在JavaScript中创建的功能应该能够显示所有6个非重复组合。
示例
输入整数
"123"
该函数应该返回：
"123, 132, 213, 231, 312, 321"
答案 0 :(得分：1)
此示例最多可接受12位数字或字母，但我敢打赌，您可以将其调整为仅允许3位数字：
<!doctype html>
<html lang="en">
<head>
<meta charset= "utf-8">
<title>Small Combinations</title>
<style>
form{font-size:1.25em}
fieldset{border:none}
input, button, label, textarea,legend{font-size:inherit; }
input, label{text-align:right; margin:0 1ex;
background-color:white;color:black;}
button{cursor:pointer}
button:hover, button:focus{color:red}
</style>
<script>
Math.factorial= function(n){
var i= n;
while(--i) n*= i;
return n;
}
//An object containing members and properties of the premutations of a set
function Combos(str){
if(!(this instanceof Combos)){
return new Combos(str);
}
str= str.replace(/\W+/g, '').toLowerCase();
var show, deep, def, cf= Combos.diffcoeff(str);
show= deep= Math.min(cf,5040);
def={
coeff: cf, count: 0,
limit: deep, next: [],
seed: str.split('').sort().join(''),
showlimit: show, text: str, items: {}
}
for(var p in def) this[p]= def[p];
}
// methods to collect the members
var MP={
collect: function(s){
var items= this.items, next= this.next, i, ch= s.split('');
for(i= 0; i < ch.length; i++){
next.push(ch.splice(i, 1));
if(ch.length== 0) items[next.join('')]= 1;
this.collect(ch.join(''));
ch.splice(i, 0, next.pop());
}
},
counter: function(){
var W= this.items, c= 0;
for(var p in W){
if(W.hasOwnProperty(p))++c;
}
return c;
},
//uses timeout to break up long calculation
getSome: function(){
if(Combos.quit){
return Combos.display(this);
}
var T= this, items= T.items, n= T.count, max= T.limit,
ch= this.seed.split(''), next, tick= 2000;
while(--tick> 0 && n< max){
next= ch.sort(function(){
return .5-Math.random()
}).join('');
if(!items[next]) items[next]= ++n;
}
T.count= n;
if(n< max){
Combos.where.value= n;
Combos.timer= setTimeout(function(){
T.getSome()
},
0);
}
else{
Combos.timer= setTimeout(function(){
Combos.display(T)
},
0);
}
}
}
for(var p in MP)Combos.prototype[p]=MP[p];
//static methods of Combos
var M1={
//calculate # of permutations
diffcoeff: function(str){
var items= {},next,
members= String(str).split('').sort(), L=members.length;
for(var i=0;i<L;i++){
tem=members[i];
if(!items[tem]) items[tem]= 1;
else ++items[tem];
}
var n= Math.factorial(str.length), g= items;
for(var p in g){
if(g.hasOwnProperty(p) && g[p]> 1){
n/= Math.factorial(g[p]);
}
}
return n;
},
// block until complete, set timer to call display
demo: function(str){
if(Combos.startTime) return;
var T= Combos(str);
Combos.where.value+= '\n';
Combos.where.ondblclick= function(){
Combos.quit= true;
}
Combos.startTime= +(new Date);
//limit the number shown- (arbitrary and optional)
if(str.length> 7) T.getSome()
else{
T.collect(T.seed);
setTimeout(function(){
T.count= T.counter();
Combos.display(T);
},
0);
}
},
// show results of calculations
display: function(A){
var W= [], L, tc= A.count, tm= +(new Date),
items= A.items, report= '',
str= A.text, coeff= A.coeff,
limit= A.showlimit;
var tm= ((tm-Combos.startTime)/1000).toFixed(3)+' sec';
if(limit){
for(var p in items){
if(items.hasOwnProperty(p)) W.push(p);
if(W.length=== limit) break;
}
}
L= W.length;
report= str+': '+coeff+' anagrams ';
if(coeff>= L){
if(coeff=== tc) report+= ' found ';
report+= '('+L +' shown)';
if(coeff> tc) report+= ' found '+tc;
}
report+= ' in '+tm+'\n\n'+W.sort().join(', ')+'\n';
Combos.where.value= report;
delete Combos.startTime;
delete Combos.quit;
Combos.where.ondblclick= '';
A.elapsed= tm;
var ins=document.getElementsByTagName('input');
ins[0].disabled= false;
ins[0].focus();
ins[0].select();
},
where: ''
}
for(var p in M1)Combos[p]=M1[p];
// page demo, set up event handlers
window.onload= function(){
var cf, str, show,
F= document.forms[0],
ins= F.getElementsByTagName('input'),
btn=F.getElementsByTagName('button')[0],
btn2=F.getElementsByTagName('button')[1],
sp=document.getElementById('showcoeff');
//run on enter
F.onsubmit=function(){
btn.onclick();
return false;// don't actually submit anything
}
Combos.where= F.getElementsByTagName('textarea')[0];
//run on click
btn.onclick= function(){
if(Combos.startTime) return;
str= ins[0].value.replace(/\W+/g, '').toLowerCase();
if(str){
sp.firstChild.data=Combos.diffcoeff(str);
ins[0].value=str;
Combos.demo(str);
}
}
}
</script>
</head>
<body>
<h1>Combinations and Permutations- 1</h1>
<form>
<fieldset>
<legend>Rearranging groups of elements</legend>
<p >
<label>Enter a word or sequence of digits:
<input size="12" maxLength="12" value="123">
</label><button type="submit">Compute</button>
</p>
<p>
</fieldset>
<h3>Unique permutations: <span id="showcoeff"> </span></h3>
<textarea cols="80" rows="20" readonly></textarea>
</p>
</form>
</body>
</html>
答案 1 :(得分：0)
这是一个非常简单的版本：http://jsfiddle.net/uXFdZ/
<script type="text/javascript">
var result = "";
function perm(s)
{
result = "";
permAux(s, 0);
}
function permAux(s, currentPos)
{
if (currentPos == s.length-1) //If the index is at the end, it's a unique permutation
result += (s + "\n");
else
for(var k = 0; k < s.length-currentPos; k++) //shifts the characters around k times, each time permutating the substring after the currentPos
permAux(circularShift(s, currentPos, k), currentPos+1);
}
function circularShift(s, startPos, shiftTimes)
{
if (shiftTimes >= s.length)
shiftTimes %= s.length;
//first substring takes the substring that will not be shifted, second and third exchange the shifted areas
return (s.substr(0, startPos) + s.substr(s.length-shiftTimes, shiftTimes) + s.substr(startPos, s.length-shiftTimes-startPos));
}
function showResults() {
var sValue = document.getElementById("number").value;
var iValue = parseInt(sValue);
if (isNaN(iValue)) {
alert("Please enter a number.");
return;
}
perm(sValue);
alert(result);
}
</script>
<input title="Please Enter a number" id="number" name="number" maxlength="3" />
<button onclick="showResults()">Go</button>
排列代码改编自here。