My attempt: def merge(lsts): sets = [set(lst) for lst in lsts if lst] merged = True while merged: merged = False results = [] while sets: common, rest = sets[0], sets[1:] sets = [] for x in rest: if x.isdisjoint(common): sets.append(x) else: merged = True common |= x results.append(common) sets = results return sets lst … Read more
As always: there is no best solution. Each solution makes different things easier or harder. The right solution for you depends on which operation you will do most. Naive Approach with parent-id: Pros: Easy to implement Easy to move a big subtree to another parent Insert is cheap Needed Fields directly accessible in SQL Cons: … Read more
You forgot the unset() in there bro. function buildTree(array &$elements, $parentId = 0) { $branch = array(); foreach ($elements as $element) { if ($element[‘parent_id’] == $parentId) { $children = buildTree($elements, $element[‘id’]); if ($children) { $element[‘children’] = $children; } $branch[$element[‘id’]] = $element; unset($elements[$element[‘id’]]); } } return $branch; }
The trick is to pass a string as the indent and to treat the last child specially: class Node { public void PrintPretty(string indent, bool last) { Console.Write(indent); if (last) { Console.Write(“\\-“); indent += ” “; } else { Console.Write(“|-“); indent += “| “; } Console.WriteLine(Name); for (int i = 0; i < Children.Count; i++) … Read more
I am wondering why the Framework doesn’t contain structures as Tree and Graph which are basic collections. Both can be regarded as sub types of Collection. This is a good question. I think it simply boils down to scoping. The core features that Collections API provides classes for are: iteration order: Lists and sorted maps … Read more
I’ve bookmarked this slidshare about SQL-Antipatterns, which discusses several alternatives: http://www.slideshare.net/billkarwin/sql-antipatterns-strike-back?src=embed The recommendation from there is to use a Closure Table (it’s explained in the slides). Here is the summary (slide 77): | Query Child | Query Subtree | Modify Tree | Ref. Integrity Adjacency List | Easy | Hard | Easy | Yes Path … Read more
From the docs: Trying to pickle a highly recursive data structure may exceed the maximum recursion depth, a RuntimeError will be raised in this case. You can carefully raise this limit with sys.setrecursionlimit(). Although your trie implementation may be simple, it uses recursion and can lead to issues when converting to a persistent data structure. … Read more
The simplest option to do what you want is probably to just use a shell escape and call find: SOURCES := $(shell find $(SOURCEDIR) -name ‘*.c’) This gets you a list of source files with paths. Note that the use of immediate assignment := rather than recursive assignment = is important here: you do not … Read more
I develop ETE, which is a python package intended, among other stuff, for programmatic tree rendering and visualization. You can create your own layout functions and produce custom tree images: It has a focus on phylogenetics, but it can actually deal with any type of hierarchical tree (clustering, decision trees, etc.)
MongoDB and CouchDB offer solutions, but not built in functionality. See this SO question on representing hierarchy in a relational database as most other NoSQL solutions I’ve seen are similar in this regard; where you have to write your own algorithms for recalculating that information as nodes are added, deleted and moved. Generally speaking you’re … Read more