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https://github.com/donnemartin/interactive-coding-challenges.git
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Add graph build order challenge
This commit is contained in:
Donne Martin
parent
3e0d78f685
commit
3051c877e5
0
graphs_trees/graph_build_order/__init__.py
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0
graphs_trees/graph_build_order/__init__.py
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242
graphs_trees/graph_build_order/build_order_challenge.ipynb
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242
graphs_trees/graph_build_order/build_order_challenge.ipynb
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@ -0,0 +1,242 @@
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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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"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)."
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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: Find a build order given a list of projects and dependencies.\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 it possible to have a cyclic graph as the input?\n",
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" * Yes\n",
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"* Can we assume we already have Graph and Node classes?\n",
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" * Yes\n",
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"* Can we assume this is a connected graph?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * Yes\n",
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"* Can we assume this fits memory?\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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"* projects: a, b, c, d, e, f, g\n",
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"* dependencies: (d, g), (f, c), (f, b), (f, a), (c, a), (b, a), (a, e), (b, e)\n",
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"* output: d, f, c, b, g, a, e\n",
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"\n",
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"Note: Edge direction is down\n",
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"<pre>\n",
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" f d\n",
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" /|\\ |\n",
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" c | b g\n",
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" \\|/|\n",
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" a |\n",
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" |/\n",
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" e\n",
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"</pre>\n",
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"\n",
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"Test a graph with a cycle, output should be None"
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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](https://github.com/donnemartin/interactive-coding-challenges/graphs_trees/build_order/build_order_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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"class Dependency(object):\n",
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"\n",
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" def __init__(self, node_key_before, node_key_after):\n",
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" self.node_key_before = node_key_before\n",
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" self.node_key_after = node_key_after"
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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 ../graph/graph.py\n",
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"%load ../graph/graph.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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"class BuildOrder(object):\n",
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"\n",
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" def __init__(self, dependencies):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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" def find_build_order(self):\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": false
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},
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"outputs": [],
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"source": [
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"# %load test_build_order.py\n",
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"from nose.tools import assert_equal\n",
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"from nose.tools import assert_true\n",
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"\n",
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"\n",
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"class TestBuildOrder(object):\n",
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"\n",
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" def __init__(self):\n",
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" self.dependencies = [\n",
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" Dependency('d', 'g'),\n",
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" Dependency('f', 'c'),\n",
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" Dependency('f', 'b'),\n",
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" Dependency('f', 'a'),\n",
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" Dependency('c', 'a'),\n",
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" Dependency('b', 'a'),\n",
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" Dependency('a', 'e'),\n",
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" Dependency('b', 'e'),\n",
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" ]\n",
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"\n",
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" def test_build_order(self):\n",
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" build_order = BuildOrder(self.dependencies)\n",
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" processed_nodes = build_order.find_build_order()\n",
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"\n",
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" expected_result0 = ('d', 'f')\n",
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" expected_result1 = ('c', 'b', 'g')\n",
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" assert_true(processed_nodes[0].key in expected_result0)\n",
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" assert_true(processed_nodes[1].key in expected_result0)\n",
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" assert_true(processed_nodes[2].key in expected_result1)\n",
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" assert_true(processed_nodes[3].key in expected_result1)\n",
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" assert_true(processed_nodes[4].key in expected_result1)\n",
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" assert_true(processed_nodes[5].key is 'a')\n",
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" assert_true(processed_nodes[6].key is 'e')\n",
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"\n",
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" print('Success: test_build_order')\n",
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"\n",
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" def test_build_order_circular(self):\n",
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" self.dependencies.append(Dependency('e', 'f'))\n",
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" build_order = BuildOrder(self.dependencies)\n",
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" processed_nodes = build_order.find_build_order()\n",
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" assert_true(processed_nodes is None)\n",
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"\n",
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" print('Success: test_build_order_circular')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestBuildOrder()\n",
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" test.test_build_order()\n",
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" test.test_build_order_circular()\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": {},
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"source": [
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"## Solution Notebook\n",
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"\n",
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"Review the [Solution Notebook](https://github.com/donnemartin/interactive-coding-challenges/graphs_trees/build_order/build_order_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 3",
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"language": "python",
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"name": "python3"
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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": 3
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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",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.4.3"
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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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310
graphs_trees/graph_build_order/build_order_solution.ipynb
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310
graphs_trees/graph_build_order/build_order_solution.ipynb
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@ -0,0 +1,310 @@
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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": [
|
||||
"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)."
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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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"# 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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"## Problem: Find a build order given a list of projects and dependencies.\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)"
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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 it possible to have a cyclic graph as the input?\n",
|
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" * Yes\n",
|
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"* Can we assume we already have Graph and Node classes?\n",
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" * Yes\n",
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"* Can we assume this is a connected graph?\n",
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" * Yes\n",
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"* Can we assume the inputs are valid?\n",
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" * Yes\n",
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"* Can we assume this fits memory?\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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"* projects: a, b, c, d, e, f, g\n",
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"* dependencies: (d, g), (f, c), (f, b), (f, a), (c, a), (b, a), (a, e), (b, e)\n",
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"* output: d, f, c, b, g, a, e\n",
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"\n",
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"Note: Edge direction is down\n",
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"<pre>\n",
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" f d\n",
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" /|\\ |\n",
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" c | b g\n",
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" \\|/|\n",
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" a |\n",
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" |/\n",
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" e\n",
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"</pre>\n",
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"\n",
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"Test a graph with a cycle, output should be None"
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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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"We can determine the build order using a topological sort.\n",
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"\n",
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"* Build the graph with projects (nodes) and dependencies (directed edges)\n",
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"* Add initially non-dependent nodes to processed_nodes\n",
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" * If none exist, we have a circular dependency, return None\n",
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"* While the length processed_nodes < the length of graph nodes\n",
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" * Remove outgoing edges from newly added items in processed_nodes\n",
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" * Add non-dependent nodes to processed_nodes\n",
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" * If we didn't add any nodes, we have a circular dependency, return None\n",
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"* Return processed_nodes\n",
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"\n",
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"Complexity:\n",
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"* Time: O(V + E)\n",
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"* Space: O(V + E)"
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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": 1,
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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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"from collections import deque\n",
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"\n",
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"\n",
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"class Dependency(object):\n",
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"\n",
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" def __init__(self, node_key_before, node_key_after):\n",
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" self.node_key_before = node_key_before\n",
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" self.node_key_after = node_key_after"
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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": 2,
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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 ../graph/graph.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": 3,
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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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"class BuildOrder(object):\n",
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"\n",
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" def __init__(self, dependencies):\n",
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" self.dependencies = dependencies\n",
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" self.graph = Graph()\n",
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" self._build_graph()\n",
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"\n",
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" def _build_graph(self):\n",
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" for dependency in self.dependencies:\n",
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" self.graph.add_edge(dependency.node_key_before,\n",
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" dependency.node_key_after)\n",
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"\n",
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" def _find_start_nodes(self, processed_nodes):\n",
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" nodes_to_process = {}\n",
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" for key, node in self.graph.nodes.items():\n",
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" if node.incoming_edges == 0 and key not in processed_nodes:\n",
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" nodes_to_process[key] = node\n",
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" return nodes_to_process\n",
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"\n",
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" def _process_nodes(self, nodes_to_process, processed_nodes):\n",
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" for node in nodes_to_process.values():\n",
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" # We'll need to iterate on copies since we'll need\n",
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" # to change the dictionaries during iteration with\n",
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" # the remove_neighbor call\n",
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" for adj_node in list(node.adj_nodes.values()):\n",
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" node.remove_neighbor(adj_node)\n",
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" processed_nodes[node.key] = node\n",
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" nodes_to_process = {}\n",
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"\n",
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" def find_build_order(self):\n",
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" result = []\n",
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" nodes_to_process = {}\n",
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" processed_nodes = {}\n",
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" while len(result) != len(self.graph.nodes):\n",
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" nodes_to_process = self._find_start_nodes(processed_nodes)\n",
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" if not nodes_to_process:\n",
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" return None\n",
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" result.extend(nodes_to_process.values())\n",
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" self._process_nodes(nodes_to_process, processed_nodes)\n",
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" return result"
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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": "code",
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"execution_count": 4,
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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": 5,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Overwriting test_build_order.py\n"
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]
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}
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],
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"source": [
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"%%writefile test_build_order.py\n",
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"from nose.tools import assert_equal\n",
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"from nose.tools import assert_true\n",
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"\n",
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"\n",
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"class TestBuildOrder(object):\n",
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"\n",
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" def __init__(self):\n",
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" self.dependencies = [\n",
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" Dependency('d', 'g'),\n",
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" Dependency('f', 'c'),\n",
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" Dependency('f', 'b'),\n",
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" Dependency('f', 'a'),\n",
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" Dependency('c', 'a'),\n",
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" Dependency('b', 'a'),\n",
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" Dependency('a', 'e'),\n",
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" Dependency('b', 'e'),\n",
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" ]\n",
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"\n",
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" def test_build_order(self):\n",
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" build_order = BuildOrder(self.dependencies)\n",
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||||
" processed_nodes = build_order.find_build_order()\n",
|
||||
"\n",
|
||||
" expected_result0 = ('d', 'f')\n",
|
||||
" expected_result1 = ('c', 'b', 'g')\n",
|
||||
" assert_true(processed_nodes[0].key in expected_result0)\n",
|
||||
" assert_true(processed_nodes[1].key in expected_result0)\n",
|
||||
" assert_true(processed_nodes[2].key in expected_result1)\n",
|
||||
" assert_true(processed_nodes[3].key in expected_result1)\n",
|
||||
" assert_true(processed_nodes[4].key in expected_result1)\n",
|
||||
" assert_true(processed_nodes[5].key is 'a')\n",
|
||||
" assert_true(processed_nodes[6].key is 'e')\n",
|
||||
"\n",
|
||||
" print('Success: test_build_order')\n",
|
||||
"\n",
|
||||
" def test_build_order_circular(self):\n",
|
||||
" self.dependencies.append(Dependency('e', 'f'))\n",
|
||||
" build_order = BuildOrder(self.dependencies)\n",
|
||||
" processed_nodes = build_order.find_build_order()\n",
|
||||
" assert_true(processed_nodes is None)\n",
|
||||
"\n",
|
||||
" print('Success: test_build_order_circular')\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"def main():\n",
|
||||
" test = TestBuildOrder()\n",
|
||||
" test.test_build_order()\n",
|
||||
" test.test_build_order_circular()\n",
|
||||
"\n",
|
||||
"\n",
|
||||
"if __name__ == '__main__':\n",
|
||||
" main()"
|
||||
]
|
||||
},
|
||||
{
|
||||
"cell_type": "code",
|
||||
"execution_count": 6,
|
||||
"metadata": {
|
||||
"collapsed": false
|
||||
},
|
||||
"outputs": [
|
||||
{
|
||||
"name": "stdout",
|
||||
"output_type": "stream",
|
||||
"text": [
|
||||
"Success: test_build_order\n",
|
||||
"Success: test_build_order_circular\n"
|
||||
]
|
||||
}
|
||||
],
|
||||
"source": [
|
||||
"%run -i test_build_order.py"
|
||||
]
|
||||
}
|
||||
],
|
||||
"metadata": {
|
||||
"kernelspec": {
|
||||
"display_name": "Python 3",
|
||||
"language": "python",
|
||||
"name": "python3"
|
||||
},
|
||||
"language_info": {
|
||||
"codemirror_mode": {
|
||||
"name": "ipython",
|
||||
"version": 3
|
||||
},
|
||||
"file_extension": ".py",
|
||||
"mimetype": "text/x-python",
|
||||
"name": "python",
|
||||
"nbconvert_exporter": "python",
|
||||
"pygments_lexer": "ipython3",
|
||||
"version": "3.5.0"
|
||||
}
|
||||
},
|
||||
"nbformat": 4,
|
||||
"nbformat_minor": 0
|
||||
}
|
||||
51
graphs_trees/graph_build_order/test_build_order.py
Normal file
51
graphs_trees/graph_build_order/test_build_order.py
Normal file
|
|
@ -0,0 +1,51 @@
|
|||
from nose.tools import assert_equal
|
||||
from nose.tools import assert_true
|
||||
|
||||
|
||||
class TestBuildOrder(object):
|
||||
|
||||
def __init__(self):
|
||||
self.dependencies = [
|
||||
Dependency('d', 'g'),
|
||||
Dependency('f', 'c'),
|
||||
Dependency('f', 'b'),
|
||||
Dependency('f', 'a'),
|
||||
Dependency('c', 'a'),
|
||||
Dependency('b', 'a'),
|
||||
Dependency('a', 'e'),
|
||||
Dependency('b', 'e'),
|
||||
]
|
||||
|
||||
def test_build_order(self):
|
||||
build_order = BuildOrder(self.dependencies)
|
||||
processed_nodes = build_order.find_build_order()
|
||||
|
||||
expected_result0 = ('d', 'f')
|
||||
expected_result1 = ('c', 'b', 'g')
|
||||
assert_true(processed_nodes[0].key in expected_result0)
|
||||
assert_true(processed_nodes[1].key in expected_result0)
|
||||
assert_true(processed_nodes[2].key in expected_result1)
|
||||
assert_true(processed_nodes[3].key in expected_result1)
|
||||
assert_true(processed_nodes[4].key in expected_result1)
|
||||
assert_true(processed_nodes[5].key is 'a')
|
||||
assert_true(processed_nodes[6].key is 'e')
|
||||
|
||||
print('Success: test_build_order')
|
||||
|
||||
def test_build_order_circular(self):
|
||||
self.dependencies.append(Dependency('e', 'f'))
|
||||
build_order = BuildOrder(self.dependencies)
|
||||
processed_nodes = build_order.find_build_order()
|
||||
assert_true(processed_nodes is None)
|
||||
|
||||
print('Success: test_build_order_circular')
|
||||
|
||||
|
||||
def main():
|
||||
test = TestBuildOrder()
|
||||
test.test_build_order()
|
||||
test.test_build_order_circular()
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Loading…
Reference in New Issue
Block a user