Tag: recursion

Building ‘limitless’ menu trees with Django

django django-models django-templates python recursion

I have a model: And want to build a template which contains menu with limitless parent-child relations for each entry, where parent id’s of the “first-level” elements is 0. And as a result to build any html menu trees I want. Answer Don’t re-invent the wheel; use a dedicated Django ext…

Skyscraper puzzle algorithm

algorithm puzzle python recursion

I’m writing an algorithm to solve skyscrapers puzzles: Skyscraper puzzles combine the row and column constraints of Sudoku with external clue values that re-imagine each row or column of numbers as a road full of skyscrapers of varying height. Higher numbers represent higher buildings. To solve a Skyscr…

Global variables in recursion. Python

global python recursion variables

OK, i’m using Python 2.7.3 and here is my code: I’m trying to modify the variable count inside the leng function. Here are the things that I’ve tried: If I put the variable count outside the lenRecur function it works fine the first time, but if I try again without restarting python shell, t…

Finding a key recursively in a dictionary

dictionary python recursion search

I’m trying to write a very simple function to recursively search through a possibly nested (in the most extreme cases ten levels deep) Python dictionary and return the first value it finds from the given key. I cannot understand why my code doesn’t work for nested dictionaries. It returns None. It…

Does Python optimize tail recursion?

python recursion tail-recursion

I have the following piece of code which fails with the following error: RuntimeError: maximum recursion depth exceeded I attempted to rewrite this to allow for tail recursion optimization (TCO). I believe that this code should have been successful if a TCO had taken place. Should I conclude that Python does …

Recursive DotDict

dictionary python recursion

I have a utility class that makes Python dictionaries behave somewhat like JavaScript objects as far as getting and setting attributes. I would like to make it so it also converts nested dictionaries into DotDict() instances. I was hoping to be able to do something like this with __init__ or __new__, but I ha…

Walking/iterating over a nested dictionary of arbitrary depth (the dictionary represents a directory tree)

dictionary iteration python recursion tree

Python newbie at time of writing. This came up because I want a user to be able to select a group of files from within a directory (and also any subdirectory), and unfortunately Tkinter’s default ability for selecting multiple files in a file dialog is broken on Windows 7 (http://bugs.python.org/issue80…

Python file parsing: Build tree from text file

algorithm python recursion tree

I have an indented text file that will be used to build a tree. Each line represents a node, and indents represent depth as well as node the current node is a child of. For example, a file might look like ROOT Node1 Node2 Node3 Node4 Node5 Node6 Which indicates that ROOT contains three children: 1, 5, and 6, …

Recursive diff of two dictionaries (keys and values)?

data-structures dictionary diff python recursion

So I have a python dictionary, call it d1, and a version of that dictionary at a later point in time, call it d2. I want to find all the changes between d1 and d2. In other words, everything that was added, removed or changed. The tricky bit is that the values can be ints, strings, lists, or dicts, so

counting odd numbers in a list python

python recursion

This is a part of my homework assignment and im close to the final answer but not quite yet. I need to write a function that counts odd numbers in a list. Create a recursive function count_odd(l) which takes as its only argument a list of integers. The function will return a count of the number of list elemen…