mirror of
https://github.com/donnemartin/interactive-coding-challenges.git
synced 2024-03-22 13:11:13 +08:00
332 lines
8.5 KiB
Python
332 lines
8.5 KiB
Python
{
|
|
"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: Implement a graph.\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 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",
|
|
"### Node\n",
|
|
"\n",
|
|
"Node will keep track of its:\n",
|
|
"* id\n",
|
|
"* visit state\n",
|
|
"* adjacent\n",
|
|
" * key: node\n",
|
|
" * value: weight\n",
|
|
"\n",
|
|
"#### add_neighhbor\n",
|
|
"\n",
|
|
"* Add the neighbor as a key and the weight as the value to `adjacent`\n",
|
|
"\n",
|
|
"Complexity:\n",
|
|
"* Time: O(1)\n",
|
|
"* Space: O(1)\n",
|
|
"\n",
|
|
"### Graph\n",
|
|
"\n",
|
|
"Graph will keep track of its:\n",
|
|
"* nodes\n",
|
|
" * key: node id\n",
|
|
" * value: node\n",
|
|
"\n",
|
|
"#### add_node\n",
|
|
"\n",
|
|
"* Create a node with the input id\n",
|
|
"* Add the newly created node to the list of nodes\n",
|
|
"\n",
|
|
"Complexity:\n",
|
|
"* Time: O(1)\n",
|
|
"* Space: O(1)\n",
|
|
"\n",
|
|
"#### add_edge\n",
|
|
"\n",
|
|
"* If the source node is not in the list of nodes, add it\n",
|
|
"* If the dest node is not in the list of nodes, add it\n",
|
|
"* Add a connection from the source node to the dest node with the given edge weight\n",
|
|
"\n",
|
|
"Complexity:\n",
|
|
"* Time: O(1)\n",
|
|
"* Space: O(1)"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {},
|
|
"source": [
|
|
"## Code"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 1,
|
|
"metadata": {
|
|
"collapsed": false
|
|
},
|
|
"outputs": [
|
|
{
|
|
"name": "stdout",
|
|
"output_type": "stream",
|
|
"text": [
|
|
"Overwriting graph.py\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"%%writefile graph.py\n",
|
|
"from enum import Enum # Python 2 users: Run pip install enum34\n",
|
|
"\n",
|
|
"\n",
|
|
"class State(Enum):\n",
|
|
" unvisited = 0\n",
|
|
" visiting = 1\n",
|
|
" visited = 2\n",
|
|
"\n",
|
|
"\n",
|
|
"class Node:\n",
|
|
"\n",
|
|
" def __init__(self, id):\n",
|
|
" self.id = id\n",
|
|
" self.visit_state = State.unvisited\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",
|
|
" self.adjacent[neighbor] = weight\n",
|
|
"\n",
|
|
"\n",
|
|
"class Graph:\n",
|
|
"\n",
|
|
" def __init__(self):\n",
|
|
" self.nodes = {} # key = node id, val = node\n",
|
|
"\n",
|
|
" def add_node(self, id):\n",
|
|
" node = Node(id)\n",
|
|
" self.nodes[id] = node\n",
|
|
" return node\n",
|
|
"\n",
|
|
" def add_edge(self, id_source, id_dest, weight=0):\n",
|
|
" if id_source not in self.nodes:\n",
|
|
" self.add_node(id_source)\n",
|
|
" if id_dest not in self.nodes:\n",
|
|
" self.add_node(id_dest)\n",
|
|
" self.nodes[id_source].add_neighbor(self.nodes[id_dest], weight)\n",
|
|
"\n",
|
|
" def add_undirected_edge(self, source, dest, weight=0):\n",
|
|
" self.add_edge(source, dest, weight)\n",
|
|
" self.nodes[dest].add_neighbor(self.nodes[source], weight)"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 2,
|
|
"metadata": {
|
|
"collapsed": false
|
|
},
|
|
"outputs": [],
|
|
"source": [
|
|
"%run graph.py"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "markdown",
|
|
"metadata": {},
|
|
"source": [
|
|
"## Unit Test"
|
|
]
|
|
},
|
|
{
|
|
"cell_type": "code",
|
|
"execution_count": 3,
|
|
"metadata": {
|
|
"collapsed": false
|
|
},
|
|
"outputs": [
|
|
{
|
|
"name": "stdout",
|
|
"output_type": "stream",
|
|
"text": [
|
|
"Overwriting test_graph.py\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"%%writefile 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": "code",
|
|
"execution_count": 4,
|
|
"metadata": {
|
|
"collapsed": false
|
|
},
|
|
"outputs": [
|
|
{
|
|
"name": "stdout",
|
|
"output_type": "stream",
|
|
"text": [
|
|
"Success: test_graph\n",
|
|
"Success: test_graph\n"
|
|
]
|
|
}
|
|
],
|
|
"source": [
|
|
"%run -i test_graph.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
|
|
}
|