In a tree where each node has exactly either 0 or 2 children, the number of nodes with 0 children is one more than the number of nodes with 2 children.{Explanation: number of nodes at height h is 2^h, which by the summation formula of a geometric series equals (sum of nodes from height 0 … Read more
larsmans answered your first question For your second question, can you simply look before you leap to avoid recursion? def makeList(self, aNode=None): if aNode is None: aNode = self.root treeaslist = [aNode.data] if aNode.lChild: treeaslist.extend(self.makeList(aNode.lChild)) if aNode.rChild: treeaslist.extend(self.makeList(aNode.rChild)) return treeaslist
I played around with domi27’s idea and came up with this. I made a nested array as my tree, [‘link’][‘sublinks’] is null or another array of more of the same. Templates The sub-template file to recurse with: <!–includes/menu-links.html–> {% for link in links %} <li> <a href=”https://stackoverflow.com/questions/8326482/{{ link.href }}”>{{ link.name }}</a> {% if link.sublinks %} … Read more
This requires a very basic recursive function to parse the child/parent pairs to a tree structure and another recursive function to print it out. Only one function would suffice but here’s two for clarity (a combined function can be found at the end of this answer). First initialize the array of child/parent pairs: $tree = … Read more
You can flatten a tree like this: IEnumerable<MyNode> Flatten(IEnumerable<MyNode> e) => e.SelectMany(c => Flatten(c.Elements)).Concat(new[] { e }); You can then filter by group using Where(…). To earn some “points for style”, convert Flatten to an extension function in a static class. public static IEnumerable<MyNode> Flatten(this IEnumerable<MyNode> e) => e.SelectMany(c => c.Elements.Flatten()).Concat(e); To earn more points … Read more
Depth first search is more memory efficient than breadth first search as you can backtrack sooner. It is also easier to implement if you use the call stack but this relies on the longest path not overflowing the stack. Also if your graph is directed then you have to not just remember if you have … Read more
The constraint is generally applied recursively to every subtree. That is, the tree is only balanced if: The left and right subtrees’ heights differ by at most one, AND The left subtree is balanced, AND The right subtree is balanced According to this, the next tree is balanced: A / \ B C / / … Read more
In the Windows command prompt you can use “tree /F” to view a tree of the current folder and all descending files & folders. In File Explorer under Windows 8.1: Select folder Press Shift, right-click mouse, and select “Open command window here” Type tree /f > tree.txt and press Enter Use MS Word to open … Read more
A radix tree is a compressed version of a trie. In a trie, on each edge you write a single letter, while in a PATRICIA tree (or radix tree) you store whole words. Now, assume you have the words hello, hat and have. To store them in a trie, it would look like: e – … Read more
You mention the most commonly implemented, which is Adjacency List: https://blogs.msdn.microsoft.com/mvpawardprogram/2012/06/25/hierarchies-convert-adjacency-list-to-nested-sets There are other models as well, including materialized path and nested sets: http://communities.bmc.com/communities/docs/DOC-9902 Joe Celko has written a book on this subject, which is a good reference from a general SQL perspective (it is mentioned in the nested set article link above). Also, Itzik … Read more