{ "cells": [ { "cell_type": "markdown", "metadata": {}, "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)." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# Challenge Notebook" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Problem: Implement a graph.\n", "\n", "* [Constraints](#Constraints)\n", "* [Test Cases](#Test-Cases)\n", "* [Algorithm](#Algorithm)\n", "* [Code](#Code)\n", "* [Unit Test](#Unit-Test)\n", "* [Solution Notebook](#Solution-Notebook)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Constraints\n", "\n", "* Is the graph directed?\n", " * Implement both\n", "* Do the edges have weights?\n", " * Yes\n", "* Can we assume the inputs are valid?\n", " * Yes" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Test Cases\n", "\n", "Input:\n", "* `add_edge(source, destination, weight)`\n", "\n", "```\n", "graph.add_edge(0, 1, 5)\n", "graph.add_edge(0, 5, 2)\n", "graph.add_edge(1, 2, 3)\n", "graph.add_edge(2, 3, 4)\n", "graph.add_edge(3, 4, 5)\n", "graph.add_edge(3, 5, 6)\n", "graph.add_edge(4, 0, 7)\n", "graph.add_edge(5, 4, 8)\n", "graph.add_edge(5, 2, 9)\n", "```\n", "\n", "Result:\n", "* `source` and `destination` nodes within `graph` are connected with specified `weight`.\n", "\n", "Note: \n", "* The Graph class will be used as a building block for more complex graph challenges." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Algorithm\n", "\n", "Refer to the [Solution Notebook](https://github.com/donnemartin/interactive-coding-challenges/graphs_trees/graphs/graph_solution.ipynb). If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Code" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": false }, "outputs": [], "source": [ "class Node:\n", "\n", " def __init__(self, id):\n", " # TODO: Implement me\n", " self.adjacent = {} # key = node, val = weight\n", "\n", " def __str__(self):\n", " return str(self.id)\n", "\n", " def add_neighbor(self, neighbor, weight=0):\n", " # TODO: Implement me\n", " pass\n", "\n", "class Graph:\n", "\n", " def __init__(self):\n", " # TODO: Implement me\n", " self.nodes = {} # key = node id, val = node\n", "\n", " def add_node(self, id):\n", " # TODO: Implement me\n", " pass\n", "\n", " def add_edge(self, source, dest, weight=0):\n", " # TODO: Implement me\n", " pass\n", "\n", " def add_undirected_edge(self, source, dest, weight=0):\n", " # TODO: Implement me\n", " pass" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Unit Test" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**The following unit test is expected to fail until you solve the challenge.**" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": false }, "outputs": [], "source": [ "# %load test_graph.py\n", "from nose.tools import assert_equal\n", "\n", "\n", "class TestGraph(object):\n", "\n", " def create_graph(self):\n", " graph = Graph()\n", " for id in range(0, 6):\n", " graph.add_node(id)\n", " return graph\n", "\n", " def test_graph(self):\n", " graph = self.create_graph()\n", "\n", " graph.add_edge(0, 1, weight=5)\n", " graph.add_edge(0, 5, weight=2)\n", " graph.add_edge(1, 2, weight=3)\n", " graph.add_edge(2, 3, weight=4)\n", " graph.add_edge(3, 4, weight=5)\n", " graph.add_edge(3, 5, weight=6)\n", " graph.add_edge(4, 0, weight=7)\n", " graph.add_edge(5, 4, weight=8)\n", " graph.add_edge(5, 2, weight=9)\n", "\n", " assert_equal(graph.nodes[0].adjacent[graph.nodes[1]], 5)\n", " assert_equal(graph.nodes[0].adjacent[graph.nodes[5]], 2)\n", " assert_equal(graph.nodes[1].adjacent[graph.nodes[2]], 3)\n", " assert_equal(graph.nodes[2].adjacent[graph.nodes[3]], 4)\n", " assert_equal(graph.nodes[3].adjacent[graph.nodes[4]], 5)\n", " assert_equal(graph.nodes[3].adjacent[graph.nodes[5]], 6)\n", " assert_equal(graph.nodes[4].adjacent[graph.nodes[0]], 7)\n", " assert_equal(graph.nodes[5].adjacent[graph.nodes[4]], 8)\n", " assert_equal(graph.nodes[5].adjacent[graph.nodes[2]], 9)\n", "\n", " print('Success: test_graph')\n", "\n", " def test_graph_undirected(self):\n", " graph = self.create_graph()\n", "\n", " graph.add_undirected_edge(0, 1, weight=5)\n", " graph.add_undirected_edge(0, 5, weight=2)\n", " graph.add_undirected_edge(1, 2, weight=3)\n", "\n", " assert_equal(graph.nodes[0].adjacent[graph.nodes[1]], 5)\n", " assert_equal(graph.nodes[1].adjacent[graph.nodes[0]], 5)\n", " assert_equal(graph.nodes[0].adjacent[graph.nodes[5]], 2)\n", " assert_equal(graph.nodes[5].adjacent[graph.nodes[0]], 2)\n", " assert_equal(graph.nodes[1].adjacent[graph.nodes[2]], 3)\n", " assert_equal(graph.nodes[2].adjacent[graph.nodes[1]], 3)\n", "\n", " print('Success: test_graph')\n", "\n", "\n", "def main():\n", " test = TestGraph()\n", " test.test_graph()\n", " test.test_graph_undirected()\n", "\n", "\n", "if __name__ == '__main__':\n", " main()" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Solution Notebook\n", "\n", "Review the [Solution Notebook](https://github.com/donnemartin/interactive-coding-challenges/graphs_trees/graphs/graph_solution.ipynb) for a discussion on algorithms and code solutions." ] } ], "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 }