mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-05 02:40:16 +00:00
516a3028d1
* Enable ruff PLR5501 rule * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
151 lines
6.4 KiB
Python
151 lines
6.4 KiB
Python
#!/usr/bin/env python3
|
|
|
|
# Author: OMKAR PATHAK, Nwachukwu Chidiebere
|
|
|
|
# Use a Python dictionary to construct the graph.
|
|
from __future__ import annotations
|
|
|
|
from pprint import pformat
|
|
from typing import Generic, TypeVar
|
|
|
|
T = TypeVar("T")
|
|
|
|
|
|
class GraphAdjacencyList(Generic[T]):
|
|
"""
|
|
Adjacency List type Graph Data Structure that accounts for directed and undirected
|
|
Graphs. Initialize graph object indicating whether it's directed or undirected.
|
|
|
|
Directed graph example:
|
|
>>> d_graph = GraphAdjacencyList()
|
|
>>> print(d_graph)
|
|
{}
|
|
>>> d_graph.add_edge(0, 1)
|
|
{0: [1], 1: []}
|
|
>>> d_graph.add_edge(1, 2).add_edge(1, 4).add_edge(1, 5)
|
|
{0: [1], 1: [2, 4, 5], 2: [], 4: [], 5: []}
|
|
>>> d_graph.add_edge(2, 0).add_edge(2, 6).add_edge(2, 7)
|
|
{0: [1], 1: [2, 4, 5], 2: [0, 6, 7], 4: [], 5: [], 6: [], 7: []}
|
|
>>> d_graph
|
|
{0: [1], 1: [2, 4, 5], 2: [0, 6, 7], 4: [], 5: [], 6: [], 7: []}
|
|
>>> print(repr(d_graph))
|
|
{0: [1], 1: [2, 4, 5], 2: [0, 6, 7], 4: [], 5: [], 6: [], 7: []}
|
|
|
|
Undirected graph example:
|
|
>>> u_graph = GraphAdjacencyList(directed=False)
|
|
>>> u_graph.add_edge(0, 1)
|
|
{0: [1], 1: [0]}
|
|
>>> u_graph.add_edge(1, 2).add_edge(1, 4).add_edge(1, 5)
|
|
{0: [1], 1: [0, 2, 4, 5], 2: [1], 4: [1], 5: [1]}
|
|
>>> u_graph.add_edge(2, 0).add_edge(2, 6).add_edge(2, 7)
|
|
{0: [1, 2], 1: [0, 2, 4, 5], 2: [1, 0, 6, 7], 4: [1], 5: [1], 6: [2], 7: [2]}
|
|
>>> u_graph.add_edge(4, 5)
|
|
{0: [1, 2],
|
|
1: [0, 2, 4, 5],
|
|
2: [1, 0, 6, 7],
|
|
4: [1, 5],
|
|
5: [1, 4],
|
|
6: [2],
|
|
7: [2]}
|
|
>>> print(u_graph)
|
|
{0: [1, 2],
|
|
1: [0, 2, 4, 5],
|
|
2: [1, 0, 6, 7],
|
|
4: [1, 5],
|
|
5: [1, 4],
|
|
6: [2],
|
|
7: [2]}
|
|
>>> print(repr(u_graph))
|
|
{0: [1, 2],
|
|
1: [0, 2, 4, 5],
|
|
2: [1, 0, 6, 7],
|
|
4: [1, 5],
|
|
5: [1, 4],
|
|
6: [2],
|
|
7: [2]}
|
|
>>> char_graph = GraphAdjacencyList(directed=False)
|
|
>>> char_graph.add_edge('a', 'b')
|
|
{'a': ['b'], 'b': ['a']}
|
|
>>> char_graph.add_edge('b', 'c').add_edge('b', 'e').add_edge('b', 'f')
|
|
{'a': ['b'], 'b': ['a', 'c', 'e', 'f'], 'c': ['b'], 'e': ['b'], 'f': ['b']}
|
|
>>> char_graph
|
|
{'a': ['b'], 'b': ['a', 'c', 'e', 'f'], 'c': ['b'], 'e': ['b'], 'f': ['b']}
|
|
"""
|
|
|
|
def __init__(self, directed: bool = True) -> None:
|
|
"""
|
|
Parameters:
|
|
directed: (bool) Indicates if graph is directed or undirected. Default is True.
|
|
"""
|
|
|
|
self.adj_list: dict[T, list[T]] = {} # dictionary of lists
|
|
self.directed = directed
|
|
|
|
def add_edge(
|
|
self, source_vertex: T, destination_vertex: T
|
|
) -> GraphAdjacencyList[T]:
|
|
"""
|
|
Connects vertices together. Creates and Edge from source vertex to destination
|
|
vertex.
|
|
Vertices will be created if not found in graph
|
|
"""
|
|
|
|
if not self.directed: # For undirected graphs
|
|
# if both source vertex and destination vertex are both present in the
|
|
# adjacency list, add destination vertex to source vertex list of adjacent
|
|
# vertices and add source vertex to destination vertex list of adjacent
|
|
# vertices.
|
|
if source_vertex in self.adj_list and destination_vertex in self.adj_list:
|
|
self.adj_list[source_vertex].append(destination_vertex)
|
|
self.adj_list[destination_vertex].append(source_vertex)
|
|
# if only source vertex is present in adjacency list, add destination vertex
|
|
# to source vertex list of adjacent vertices, then create a new vertex with
|
|
# destination vertex as key and assign a list containing the source vertex
|
|
# as it's first adjacent vertex.
|
|
elif source_vertex in self.adj_list:
|
|
self.adj_list[source_vertex].append(destination_vertex)
|
|
self.adj_list[destination_vertex] = [source_vertex]
|
|
# if only destination vertex is present in adjacency list, add source vertex
|
|
# to destination vertex list of adjacent vertices, then create a new vertex
|
|
# with source vertex as key and assign a list containing the source vertex
|
|
# as it's first adjacent vertex.
|
|
elif destination_vertex in self.adj_list:
|
|
self.adj_list[destination_vertex].append(source_vertex)
|
|
self.adj_list[source_vertex] = [destination_vertex]
|
|
# if both source vertex and destination vertex are not present in adjacency
|
|
# list, create a new vertex with source vertex as key and assign a list
|
|
# containing the destination vertex as it's first adjacent vertex also
|
|
# create a new vertex with destination vertex as key and assign a list
|
|
# containing the source vertex as it's first adjacent vertex.
|
|
else:
|
|
self.adj_list[source_vertex] = [destination_vertex]
|
|
self.adj_list[destination_vertex] = [source_vertex]
|
|
# For directed graphs
|
|
# if both source vertex and destination vertex are present in adjacency
|
|
# list, add destination vertex to source vertex list of adjacent vertices.
|
|
elif source_vertex in self.adj_list and destination_vertex in self.adj_list:
|
|
self.adj_list[source_vertex].append(destination_vertex)
|
|
# if only source vertex is present in adjacency list, add destination
|
|
# vertex to source vertex list of adjacent vertices and create a new vertex
|
|
# with destination vertex as key, which has no adjacent vertex
|
|
elif source_vertex in self.adj_list:
|
|
self.adj_list[source_vertex].append(destination_vertex)
|
|
self.adj_list[destination_vertex] = []
|
|
# if only destination vertex is present in adjacency list, create a new
|
|
# vertex with source vertex as key and assign a list containing destination
|
|
# vertex as first adjacent vertex
|
|
elif destination_vertex in self.adj_list:
|
|
self.adj_list[source_vertex] = [destination_vertex]
|
|
# if both source vertex and destination vertex are not present in adjacency
|
|
# list, create a new vertex with source vertex as key and a list containing
|
|
# destination vertex as it's first adjacent vertex. Then create a new vertex
|
|
# with destination vertex as key, which has no adjacent vertex
|
|
else:
|
|
self.adj_list[source_vertex] = [destination_vertex]
|
|
self.adj_list[destination_vertex] = []
|
|
|
|
return self
|
|
|
|
def __repr__(self) -> str:
|
|
return pformat(self.adj_list)
|