mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
284 lines
6.7 KiB
Plaintext
284 lines
6.7 KiB
Plaintext
{
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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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"# 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: 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)"
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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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" * Yes\n",
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"* Do the edges have weights?\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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"* We'll be using an OrderedDict to make the outputs more consistent and simplify our testing.\n",
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"* Graph 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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"### Node\n",
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"\n",
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"Node will keep track of its:\n",
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"* id\n",
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"* visit state\n",
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"* adjacent\n",
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" * key: node\n",
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" * value: weight\n",
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"\n",
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"### Graph\n",
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"\n",
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"Graph will keep track of its:\n",
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"* nodes\n",
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" * key: node id\n",
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" * value: node\n",
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"\n",
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"#### add_node\n",
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"\n",
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"* Create a node with the input id\n",
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"* Add the newly created node to the list of nodes\n",
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"\n",
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"Complexity:\n",
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"* Time: O(1)\n",
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"* Space: O(1)\n",
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"\n",
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"#### add_edge\n",
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"\n",
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"* If the source node is not in the list of nodes, add it\n",
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"* If the dest node is not in the list of nodes, add it\n",
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"* Add a connection from the source node to the dest node with the given edge weight\n",
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"\n",
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"Complexity:\n",
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"* Time: O(1)\n",
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"* Space: O(1)"
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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": 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 graph.py\n"
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]
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}
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],
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"source": [
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"%%writefile graph.py\n",
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"from collections import OrderedDict\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, id):\n",
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" self.id = id\n",
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" self.visited = False\n",
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" self.adjacent = OrderedDict() # key = node, val = weight\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 = OrderedDict() # key = node id, val = node\n",
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"\n",
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" def add_node(self, id):\n",
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" node = Node(id)\n",
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" self.nodes[id] = node\n",
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" return node\n",
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"\n",
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" def add_edge(self, source, dest, weight=0):\n",
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" if source not in self.nodes:\n",
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" self.add_node(source)\n",
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" if dest not in self.nodes:\n",
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" self.add_node(dest)\n",
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" self.nodes[source].adjacent[self.nodes[dest]] = weight"
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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": false
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},
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"outputs": [],
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"source": [
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"%run graph.py"
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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": 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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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Overwriting test_graph.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_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 test_graph(self):\n",
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" graph = Graph()\n",
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" for id in range(0, 6):\n",
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" graph.add_node(id)\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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" assert_equal(graph.nodes[0].adjacent[graph.nodes[1]], 5)\n",
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" assert_equal(graph.nodes[0].adjacent[graph.nodes[5]], 2)\n",
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" assert_equal(graph.nodes[1].adjacent[graph.nodes[2]], 3)\n",
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" assert_equal(graph.nodes[2].adjacent[graph.nodes[3]], 4)\n",
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" assert_equal(graph.nodes[3].adjacent[graph.nodes[4]], 5)\n",
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" assert_equal(graph.nodes[3].adjacent[graph.nodes[5]], 6)\n",
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" assert_equal(graph.nodes[4].adjacent[graph.nodes[0]], 7)\n",
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" assert_equal(graph.nodes[5].adjacent[graph.nodes[4]], 8)\n",
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" assert_equal(graph.nodes[5].adjacent[graph.nodes[2]], 9)\n",
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"\n",
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" print('Success: test_graph')\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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"\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": "code",
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"execution_count": 4,
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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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"Success: test_graph\n"
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]
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}
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],
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"source": [
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"%run -i test_graph.py"
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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",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython2",
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"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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