Nodejs Array Permutation permutations(n)

Method Source Code

/* Generate all permutations.
 * Use it with n = Array.length */

Array.prototype.permutations = function(n){
  var perms = [],
      array = this;//  w  w w.j  a  v  a  2s.  com
  var compute_perms = function(n){
    if(n==1)
      perms.push(array.join(''));
    else{
      for(var i=0; i!=n; i++){
        compute_perms(n-1);
        array.swap(n%2?0:i, n-1);
      }
    }
  }
  compute_perms(n);
  return perms;
}

Related

1. permutationsArray_permutations()

   "use strict";
   Array.prototype.permutations = function Array_permutations() {
       if (this.length === 1) {
           return [this];
       var permutations = [],
           tmp, fixed;
       for (var i=0; i<this.length; i++) {
           tmp = this.slice();
   ...
   

2. permute(len)

   Array.prototype.permute = function(len) {
       var ret = [];
       for (var i = 0; i < this.length; i++) {
           var c = this[i];
           if (len > 1) {
               var sub = this.permute(len - 1);
               for (var j = 0; j < sub.length; j++) {
                   ret.push(c + sub[j]);
           } else return this;
       return ret;
   };