mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
285 lines
8.6 KiB
Python
285 lines
8.6 KiB
Python
{
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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: Implement a graph.\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 the graph directed?\n",
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" * Implement both\n",
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"* Do the edges have weights?\n",
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" * Yes\n",
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"* Can the graph have cycles?\n",
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" * Yes\n",
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"* If we try to add a node that already exists, do we just do nothing?\n",
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" * Yes\n",
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"* If we try to delete a node that doesn't exist, do we just do nothing?\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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"Input:\n",
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"* `add_edge(source, destination, weight)`\n",
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"\n",
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"```\n",
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"graph.add_edge(0, 1, 5)\n",
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"graph.add_edge(0, 5, 2)\n",
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"graph.add_edge(1, 2, 3)\n",
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"graph.add_edge(2, 3, 4)\n",
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"graph.add_edge(3, 4, 5)\n",
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"graph.add_edge(3, 5, 6)\n",
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"graph.add_edge(4, 0, 7)\n",
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"graph.add_edge(5, 4, 8)\n",
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"graph.add_edge(5, 2, 9)\n",
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"```\n",
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"\n",
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"Result:\n",
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"* `source` and `destination` nodes within `graph` are connected with specified `weight`.\n",
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"\n",
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"Note: \n",
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"* The Graph class will be used as a building block for more complex graph 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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"## Algorithm\n",
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"\n",
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"Refer to the [Solution Notebook](http://nbviewer.jupyter.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph/graph_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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"outputs": [],
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"source": [
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"from enum import Enum # Python 2 users: Run pip install enum34\n",
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"\n",
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"\n",
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"class State(Enum):\n",
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"\n",
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" unvisited = 0\n",
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" visiting = 1\n",
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" visited = 2\n",
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"\n",
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"\n",
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"class Node:\n",
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"\n",
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" def __init__(self, key):\n",
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" self.key = key\n",
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" self.visit_state = State.unvisited\n",
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" self.incoming_edges = 0\n",
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" self.adj_nodes = {} # Key = key, val = Node\n",
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" self.adj_weights = {} # Key = Node, val = weight\n",
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"\n",
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" def __repr__(self):\n",
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" return str(self.key)\n",
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"\n",
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" def __lt__(self, other):\n",
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" return self.key < other.key\n",
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"\n",
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" def add_neighbor(self, neighbor, weight=0):\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 remove_neighbor(self, neighbor):\n",
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" # TODO: Implement me\n",
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" pass\n",
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"\n",
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"\n",
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"class Graph:\n",
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"\n",
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" def __init__(self):\n",
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" self.nodes = {} # Key = key, val = Node\n",
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"\n",
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" def add_node(self, id):\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 add_edge(self, source, dest, weight=0):\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 add_undirected_edge(self, source, dest, weight=0):\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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"outputs": [],
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"source": [
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"# %load test_graph.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 TestGraph(object):\n",
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"\n",
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" def create_graph(self):\n",
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" graph = Graph()\n",
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" for key in range(0, 6):\n",
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" graph.add_node(key)\n",
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" return graph\n",
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"\n",
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" def test_graph(self):\n",
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" graph = self.create_graph()\n",
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" graph.add_edge(0, 1, weight=5)\n",
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" graph.add_edge(0, 5, weight=2)\n",
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" graph.add_edge(1, 2, weight=3)\n",
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" graph.add_edge(2, 3, weight=4)\n",
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" graph.add_edge(3, 4, weight=5)\n",
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" graph.add_edge(3, 5, weight=6)\n",
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" graph.add_edge(4, 0, weight=7)\n",
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" graph.add_edge(5, 4, weight=8)\n",
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" graph.add_edge(5, 2, weight=9)\n",
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"\n",
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" assert_equal(graph.nodes[0].adj_weights[graph.nodes[1].key], 5)\n",
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" assert_equal(graph.nodes[0].adj_weights[graph.nodes[5].key], 2)\n",
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" assert_equal(graph.nodes[1].adj_weights[graph.nodes[2].key], 3)\n",
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" assert_equal(graph.nodes[2].adj_weights[graph.nodes[3].key], 4)\n",
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" assert_equal(graph.nodes[3].adj_weights[graph.nodes[4].key], 5)\n",
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" assert_equal(graph.nodes[3].adj_weights[graph.nodes[5].key], 6)\n",
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" assert_equal(graph.nodes[4].adj_weights[graph.nodes[0].key], 7)\n",
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" assert_equal(graph.nodes[5].adj_weights[graph.nodes[4].key], 8)\n",
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" assert_equal(graph.nodes[5].adj_weights[graph.nodes[2].key], 9)\n",
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"\n",
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" assert_equal(graph.nodes[0].incoming_edges, 1)\n",
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" assert_equal(graph.nodes[1].incoming_edges, 1)\n",
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" assert_equal(graph.nodes[2].incoming_edges, 2)\n",
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" assert_equal(graph.nodes[3].incoming_edges, 1)\n",
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" assert_equal(graph.nodes[4].incoming_edges, 2)\n",
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" assert_equal(graph.nodes[5].incoming_edges, 2)\n",
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"\n",
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" graph.nodes[0].remove_neighbor(graph.nodes[1])\n",
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" assert_equal(graph.nodes[1].incoming_edges, 0)\n",
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" graph.nodes[3].remove_neighbor(graph.nodes[4])\n",
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" assert_equal(graph.nodes[4].incoming_edges, 1)\n",
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"\n",
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" assert_equal(graph.nodes[0] < graph.nodes[1], True)\n",
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"\n",
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" print('Success: test_graph')\n",
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"\n",
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" def test_graph_undirected(self):\n",
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" graph = self.create_graph()\n",
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" graph.add_undirected_edge(0, 1, weight=5)\n",
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" graph.add_undirected_edge(0, 5, weight=2)\n",
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" graph.add_undirected_edge(1, 2, weight=3)\n",
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"\n",
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" assert_equal(graph.nodes[0].adj_weights[graph.nodes[1].key], 5)\n",
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" assert_equal(graph.nodes[1].adj_weights[graph.nodes[0].key], 5)\n",
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" assert_equal(graph.nodes[0].adj_weights[graph.nodes[5].key], 2)\n",
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" assert_equal(graph.nodes[5].adj_weights[graph.nodes[0].key], 2)\n",
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" assert_equal(graph.nodes[1].adj_weights[graph.nodes[2].key], 3)\n",
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" assert_equal(graph.nodes[2].adj_weights[graph.nodes[1].key], 3)\n",
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"\n",
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" print('Success: test_graph_undirected')\n",
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"\n",
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"\n",
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"def main():\n",
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" test = TestGraph()\n",
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" test.test_graph()\n",
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" test.test_graph_undirected()\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/graphs/graph_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": "3.6.4"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 1
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}
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