Talk:Heap's algorithm

This article needs to be enhanced. It looks like this algorithm is a good solution to the problem. It is quite nice that it is short and works, and in 1963 it was most important to reduce complexity and memory consumption. But if you look what it does (the picture is very helpful with that) it is quite weird and does lots of unnecessary swaps. So, the pro and contra, and other algorithms like Steinhaus–Johnson–Trotter algorithm should be mentioned. 5.146.194.61 (talk) 14:53, 8 October 2014 (UTC)[reply]

Please fix it! Feel free to add at least a "see also" section that links to the other algorithm, and if you have source that compares algorithms, be sure to cite it. QVVERTYVS (hm?) 09:34, 9 October 2014 (UTC)[reply]

An Implementation in Javascript

I implemented this algorithm in Javascript based on the pseudocode from this article, as closely as possible. I had found the algorithm a little difficult to understand without a working implementation, & hope this can help others. I didn't add this link to the Article itself, to avoid violating WP:NOR. http://dsernst.com/2014/12/14/heaps-permutation-algorithm-in-javascript/ Thanks! --dsernst (talk) 09:52, 4 January 2015 (UTC)[reply]

Incorrect algorithm

The extra swaps stem from swapping in the last iteration of the for loop, are not a part of Heap's algorithm. I compared with Sedgewick (1977). I will correct the article, but this means that the nice illustration is out of date, and will be removed. sverdrup (talk) 11:48, 29 June 2015 (UTC)[reply]

Correct(?) Algorithm

The last edit to the algorithm itself (where the range of iteration has been changed from [0,n-1] to [0,n-2]) did not work, so I changed it back to [0,n-1].

I have no access to the Sedgewick 1977 paper, but according to the other 'paper'(more like presentation) the genuine range is [0,n-1]. — Preceding unsigned comment added by 5.43.65.114 (talk) 22:41, 18 August 2015 (UTC)[reply]

Correct non recursive Algorithm

The non recursive implementation of Heap's algorithm proposed in the link number 3 (Sedgewick's pdf) can't work. It seems plagued by, really, a lot of errors or typos. Meanwhile, using the ideas of the link one can get a working implementation. Unfortunately the one I get is much less stylish, not even mentioning time efficiency.

// doit() is whatever shall be done with a new permutation of the N elements of table t
void exchange(int *t,int n, int i,int j){
  int b;
  b = t[i]; t[i] = t[j]; t[j] = b;
}
void permutate(int*t, int N){
  int n,i,j;
  int c[N],tt[N];
  for(i=0; i<N; i++){
    c[i] = 0; tt[i] = t[i];}
  for(j=0;j<N;j++) {exchange(t,N,j,c[j]);}
  //doit();
  for(i=1;i<N;){
    if(c[i] < i){
      c[i]++; i=1; 
      for(j=0;j<N;j++) {t[j] = tt[j];}
      for(j=0;j<N;j++) {exchange(t,N,j,c[j]);}
      //doit();
    } else {
      c[i++] = 0;
    }
  }
}

— Preceding unsigned comment added by 192.93.101.133 (talk • contribs) 11:44 6 January 2016