全排列javascript算法

全排列算法：

1.利用数组实现
<script>
function getNumberLoop(arr){
if(arr.length<2){
return arr;
}else if(arr.length==2){
var newArray=new Array();
newArray[0]=arr;
newArray[1]=new Array();
newArray[1][0]=arr[1];
newArray[1][1]=arr[0];
return newArray;
}else{
var item=arr.splice(0,1);
var arr=getNumberLoop(arr);
var newArray=new Array();
for(var i=0;i<arr.length;i++){
for(var j=0;j<=arr[i].length;j++){
var spliceArray=new Array();
for(var k=0;k<arr[i].length;k++){
spliceArray[k]=arr[i][k];
}
spliceArray.splice(j,0,item);
newArray[i*(arr[i].length+1)+j]=spliceArray;
}
}
return newArray;
}
}
var array=['A','B','C','D','E'];
alert(getNumberLoop(array).length);
</script>

2.利用字符串实现
<script>
function getNumberLoop(str){
if(str.length<2){
return new Array(str);
}else if(str.length==2){
var newArray=new Array();
newArray[0]=str.charAt(0)+str.charAt(1);
newArray[1]=str.charAt(1)+str.charAt(0);
return newArray;
}else{
var Char=str.charAt(0);
var str=str.slice(1);
var arr=getNumberLoop(str);
var newArray=new Array();
for(var i=0;i<arr.length;i++){
for(var j=0;j<=arr[i].length;j++){
var sliceStr=arr[i];
sliceStr=sliceStr.slice(0,j)+Char+sliceStr.slice(j);
newArray[i*(arr[i].length+1)+j]=sliceStr;
}
}
return newArray;
}
}
var string="ABCD"
alert(getNumberLoop(string));
</script>