mirror of
https://github.com/donnemartin/interactive-coding-challenges
synced 2026-01-03 16:08:02 +00:00
Added tree level lists challenge.
This commit is contained in:
Donne Martin
@@ -207,6 +207,7 @@ Challenges, solutions, and unit tests are presented in the form of **IPython/Jup
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| Implement breadth-first search on a tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_bfs/bfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_bfs/bfs_solution.ipynb) |
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| Determine the height of a tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_height/height_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_height/height_solution.ipynb) |
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| Create a binary search tree with minimal height from a sorted array | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_min/bst_min_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_min/bst_min_solution.ipynb) |
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| Create a linked list for each level of a binary tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb) |
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| Implement a binary search tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst/bst_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst/bst_solution.ipynb) |
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| Implement depth-first search on a graph | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_dfs/dfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_dfs/dfs_solution.ipynb) |
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| Implement breadth-first search on a graph | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_bfs/bfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_bfs/bfs_solution.ipynb) |
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0
graphs_trees/tree_level_lists/__init__.py
Normal file
0
graphs_trees/tree_level_lists/__init__.py
Normal file
42
graphs_trees/tree_level_lists/test_tree_level_lists.py
Normal file
42
graphs_trees/tree_level_lists/test_tree_level_lists.py
Normal file
@@ -0,0 +1,42 @@
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from nose.tools import assert_equal
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class TestTreeLevelLists(object):
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def test_tree_level_lists(self):
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node = Node(5)
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insert(node, 3)
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insert(node, 8)
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insert(node, 2)
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insert(node, 4)
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insert(node, 1)
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insert(node, 7)
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insert(node, 6)
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insert(node, 9)
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insert(node, 10)
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insert(node, 11)
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levels = create_level_lists(node)
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results_list = []
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for level in levels:
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results = Results()
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for node in level:
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results.add_result(node)
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results_list.append(results)
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assert_equal(str(results_list[0]), '[5]')
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assert_equal(str(results_list[1]), '[3, 8]')
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assert_equal(str(results_list[2]), '[2, 4, 7, 9]')
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assert_equal(str(results_list[3]), '[1, 6, 10]')
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assert_equal(str(results_list[4]), '[11]')
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print('Success: test_tree_level_lists')
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def main():
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test = TestTreeLevelLists()
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test.test_tree_level_lists()
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if __name__ == '__main__':
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main()
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202
graphs_trees/tree_level_lists/tree_level_lists_challenge.ipynb
Normal file
202
graphs_trees/tree_level_lists/tree_level_lists_challenge.ipynb
Normal file
@@ -0,0 +1,202 @@
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{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<small><i>This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges).</i></small>"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Challenge Notebook"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Problem: Create a linked list for each level of a binary tree.\n",
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"\n",
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"* [Constraints](#Constraints)\n",
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"* [Test Cases](#Test-Cases)\n",
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"* [Algorithm](#Algorithm)\n",
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"* [Code](#Code)\n",
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"* [Unit Test](#Unit-Test)\n",
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"* [Solution Notebook](#Solution-Notebook)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Constraints\n",
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"\n",
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"* Is this a binary search tree?\n",
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" * Yes\n",
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"* Can we assume we already have a Node class with an insert method?\n",
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" * Yes"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Test Cases\n",
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"\n",
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"* 5, 3, 8, 2, 4, 1, 7, 6, 9, 10, 11 -> [[5], [3, 8], [2, 4, 7, 9], [1, 6, 10], [11]]"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Algorithm\n",
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"\n",
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"Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Code"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"%run ../bst/bst.py\n",
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"%load ../bst/bst.py"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"def create_level_lists(root):\n",
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" # TODO: Implement me\n",
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" pass"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
|
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"## Unit Test"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"**The following unit test is expected to fail until you solve the challenge.**"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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||||
"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
|
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"%run ../utils/results.py"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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||||
"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"# %load test_tree_level_lists.py\n",
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"from nose.tools import assert_equal\n",
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"\n",
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"\n",
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"class TestTreeLevelLists(object):\n",
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"\n",
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" def test_tree_level_lists(self):\n",
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" node = Node(5)\n",
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" insert(node, 3)\n",
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" insert(node, 8)\n",
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" insert(node, 2)\n",
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" insert(node, 4)\n",
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" insert(node, 1)\n",
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" insert(node, 7)\n",
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" insert(node, 6)\n",
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" insert(node, 9)\n",
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" insert(node, 10)\n",
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" insert(node, 11)\n",
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"\n",
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" levels = create_level_lists(node)\n",
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" results_list = []\n",
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" for level in levels:\n",
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" results = Results()\n",
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" for node in level:\n",
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" results.add_result(node)\n",
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" results_list.append(results)\n",
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"\n",
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" assert_equal(str(results_list[0]), '[5]')\n",
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" assert_equal(str(results_list[1]), '[3, 8]')\n",
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" assert_equal(str(results_list[2]), '[2, 4, 7, 9]')\n",
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" assert_equal(str(results_list[3]), '[1, 6, 10]')\n",
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" assert_equal(str(results_list[4]), '[11]')\n",
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"\n",
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" print('Success: test_tree_level_lists')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestTreeLevelLists()\n",
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" test.test_tree_level_lists()\n",
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"\n",
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"\n",
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"if __name__ == '__main__':\n",
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" main()"
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]
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},
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||||
{
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"cell_type": "markdown",
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"metadata": {},
|
||||
"source": [
|
||||
"## Solution Notebook\n",
|
||||
"\n",
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||||
"Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb) for a discussion on algorithms and code solutions."
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 2",
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"language": "python",
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"name": "python2"
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},
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"language_info": {
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||||
"codemirror_mode": {
|
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"name": "ipython",
|
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"version": 2
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},
|
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"file_extension": ".py",
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"mimetype": "text/x-python",
|
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"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython2",
|
||||
"version": "2.7.10"
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}
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},
|
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"nbformat": 4,
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"nbformat_minor": 0
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}
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239
graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb
Normal file
239
graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb
Normal file
@@ -0,0 +1,239 @@
|
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{
|
||||
"cells": [
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"<small><i>This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges).</i></small>"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"# Solution Notebook"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Problem: Create a linked list for each level of a binary tree.\n",
|
||||
"\n",
|
||||
"* [Constraints](#Constraints)\n",
|
||||
"* [Test Cases](#Test-Cases)\n",
|
||||
"* [Algorithm](#Algorithm)\n",
|
||||
"* [Code](#Code)\n",
|
||||
"* [Unit Test](#Unit-Test)"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Constraints\n",
|
||||
"\n",
|
||||
"* Is this a binary search tree?\n",
|
||||
" * Yes\n",
|
||||
"* Can we assume we already have a Node class with an insert method?\n",
|
||||
" * Yes"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Test Cases\n",
|
||||
"\n",
|
||||
"* 5, 3, 8, 2, 4, 1, 7, 6, 9, 10, 11 -> [[5], [3, 8], [2, 4, 7, 9], [1, 6, 10], [11]]"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
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"## Algorithm\n",
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"\n",
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"We can use either a depth-first or a breadth-first search. Intuitively, it seems like a breadth-first search might be a better fit as we are creating a linked list for each level.\n",
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"\n",
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"We can use a modified breadth-first search that keeps track of parents as we build the linked list for the current level.\n",
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"\n",
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"* Append the root to the current level's linked list `current`\n",
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"* While the `current` is not empty:\n",
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" * Add `current` to `results`\n",
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" * Set `parents` to `current` to prepare to go one level deeper\n",
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" * Clear `current` so it can hold the next level\n",
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" * For each `parent` in `parents`, add the children to `current`\n",
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"* Return the results\n",
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" \n",
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"Complexity:\n",
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"* Time: O(n)\n",
|
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"* Space: O(n)"
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]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Code"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 1,
|
||||
"metadata": {
|
||||
"collapsed": true
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"%run ../bst/bst.py"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 2,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"def create_level_lists(root):\n",
|
||||
" if root is None:\n",
|
||||
" return\n",
|
||||
" results = []\n",
|
||||
" current = []\n",
|
||||
" parents = []\n",
|
||||
" current.append(root)\n",
|
||||
" while current:\n",
|
||||
" results.append(current)\n",
|
||||
" parents = list(current)\n",
|
||||
" current = []\n",
|
||||
" for parent in parents:\n",
|
||||
" if parent.left is not None:\n",
|
||||
" current.append(parent.left)\n",
|
||||
" if parent.right is not None:\n",
|
||||
" current.append(parent.right)\n",
|
||||
" return results"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "markdown",
|
||||
"metadata": {},
|
||||
"source": [
|
||||
"## Unit Test"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 3,
|
||||
"metadata": {
|
||||
"collapsed": true
|
||||
},
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"%run ../utils/results.py"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 4,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Overwriting test_tree_level_lists.py\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%%writefile test_tree_level_lists.py\n",
|
||||
"from nose.tools import assert_equal\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"class TestTreeLevelLists(object):\n",
|
||||
"\n",
|
||||
" def test_tree_level_lists(self):\n",
|
||||
" node = Node(5)\n",
|
||||
" insert(node, 3)\n",
|
||||
" insert(node, 8)\n",
|
||||
" insert(node, 2)\n",
|
||||
" insert(node, 4)\n",
|
||||
" insert(node, 1)\n",
|
||||
" insert(node, 7)\n",
|
||||
" insert(node, 6)\n",
|
||||
" insert(node, 9)\n",
|
||||
" insert(node, 10)\n",
|
||||
" insert(node, 11)\n",
|
||||
"\n",
|
||||
" levels = create_level_lists(node)\n",
|
||||
" results_list = []\n",
|
||||
" for level in levels:\n",
|
||||
" results = Results()\n",
|
||||
" for node in level:\n",
|
||||
" results.add_result(node)\n",
|
||||
" results_list.append(results)\n",
|
||||
"\n",
|
||||
" assert_equal(str(results_list[0]), '[5]')\n",
|
||||
" assert_equal(str(results_list[1]), '[3, 8]')\n",
|
||||
" assert_equal(str(results_list[2]), '[2, 4, 7, 9]')\n",
|
||||
" assert_equal(str(results_list[3]), '[1, 6, 10]')\n",
|
||||
" assert_equal(str(results_list[4]), '[11]')\n",
|
||||
"\n",
|
||||
" print('Success: test_tree_level_lists')\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestTreeLevelLists()\n",
|
||||
" test.test_tree_level_lists()\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"if __name__ == '__main__':\n",
|
||||
" main()"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 5,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Success: test_tree_level_lists\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%run -i test_tree_level_lists.py"
|
||||
]
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
"kernelspec": {
|
||||
"display_name": "Python 2",
|
||||
"language": "python",
|
||||
"name": "python2"
|
||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 2
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
||||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython2",
|
||||
"version": "2.7.10"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
Reference in New Issue
Block a user