## digitalmars.D.learn - Keep Track of the Best N Nodes in a Graph Traversal Algorithm

- "Per =?UTF-8?B?Tm9yZGzDtnci?= <per.nordlow gmail.com> (14/14) Mar 25 2015 I have graph traversal algorithm that needs to keep track of the
- bearophile (4/6) Mar 25 2015 std.algorithm.topNCopy?
- "Per =?UTF-8?B?Tm9yZGzDtnci?= <per.nordlow gmail.com> (4/10) Mar 25 2015 Could you please elaborate a bit how you mean this should be
- "Per =?UTF-8?B?Tm9yZGzDtnci?= <per.nordlow gmail.com> (4/10) Mar 25 2015 Notice that, ideally, I would like my list of top-nodes to have a
- Tobias Pankrath (2/15) Mar 25 2015 What's wrong with binary heaps?
- =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= (6/7) Mar 25 2015 Ahh, a Binary Heap perfectly matches my needs.
- bearophile (4/7) Mar 25 2015 But isn't topNCopy using a heap?

I have graph traversal algorithm that needs to keep track of the N "best" node visit. Every time a visit a new node I get its goodness along with a ref to it. I then want to compare it to every currently best node in this list and replace it with the worst one if its better than the worst. How do I most easily do this with regards to minimizing GC-usage. For N = 3 I mean something like this: (A,1) => [(A,1)] (B,2) => [(A,1), (B,2)] (C,3) => [(A,1), (B,2), (C,3)] (X,0) => [(X,0), (A,1), (B,2)] (Y,1) => [(X,0), (Y,1), (A,1)] ... (A,1) means we just visited node with goodness (distance) 1

Mar 25 2015

Nordlöw:I have graph traversal algorithm that needs to keep track of the N "best" node visit.std.algorithm.topNCopy? Bye, bearophile

Mar 25 2015

On Wednesday, 25 March 2015 at 13:55:29 UTC, bearophile wrote:Nordlöw:Could you please elaborate a bit how you mean this should be used. Notice that the number of visited nodes are in the millions or perhaps even tens of millions. And N is typically 100-1000.I have graph traversal algorithm that needs to keep track of the N "best" node visit.std.algorithm.topNCopy? Bye, bearophile

Mar 25 2015

On Wednesday, 25 March 2015 at 13:55:29 UTC, bearophile wrote:Nordlöw:Notice that, ideally, I would like my list of top-nodes to have a fixed size during the whole algorithm (99.9 % of time) as soon it has reached the length of N.I have graph traversal algorithm that needs to keep track of the N "best" node visit.std.algorithm.topNCopy? Bye, bearophile

Mar 25 2015

On Wednesday, 25 March 2015 at 14:40:28 UTC, Per Nordlöw wrote:On Wednesday, 25 March 2015 at 13:55:29 UTC, bearophile wrote:What's wrong with binary heaps?I have graph traversal algorithm that needs to keep track of the N "best" node visit.std.algorithm.topNCopy? Bye, bearophile

Mar 25 2015

On Wednesday, 25 March 2015 at 17:49:49 UTC, Tobias Pankrath wrote:What's wrong with binary heaps?Ahh, a Binary Heap perfectly matches my needs. https://en.wikipedia.org/wiki/Binary_heap http://dlang.org/phobos/std_container_binaryheap.html Thx

Mar 25 2015

Nordlöw:Ahh, a Binary Heap perfectly matches my needs. https://en.wikipedia.org/wiki/Binary_heap http://dlang.org/phobos/std_container_binaryheap.htmlBut isn't topNCopy using a heap? Bye, bearophile

Mar 25 2015