全排列算法 --javascript 实现

(function(){

var ret = new Array();

var A = function a(str){
if(str == undefined || str == null){return new Array();}
if(str.length < 2) {return new Array(str);}
if(str.length == 2) {return new Array(str[0]+str[1],str[1]+str[0]);}

for(var k = 0;k < str.length; k++){

var current = str[k];
if(k == 0){
sub = str.substr(1,str.length-1);
}
else if(k == str.length-1){
sub = str.substr(0,str.length-1);
}
else{
var sub1 = str.substr(0,k);
var sub2 = str.substr(k+1,str.length-1); 

sub = sub1+sub2;
}
console.log("sub : " + sub + ", current : " + current);
var arr = a(sub);

var r = new Array();
for(var i =0 ;i < arr.length; i++){
var ar = arr[i];
for(var j = 0 ;j < arr.length + 1; j++){
var tmp = insert(ar,current,j);
if(ret.indexOf(tmp) == -1 ){ret.push(tmp);r.push(tmp);}
}
}

return r;
}

};

var insert = function (oristr,s,p){
if(p == 0){
return s+oristr;
}
if(p >= oristr.length){
return oristr + s;
}
else{
var sub1 = oristr.substr(0,p);
var sub2 = oristr.substr(p,oristr.length-1); 

return sub1+s+sub2;
}

};

var r = A("abcde");
console.log(r);

})();

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