mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-27 23:11:09 +00:00
59 lines
1.4 KiB
Python
59 lines
1.4 KiB
Python
"""
|
|
https://en.wikipedia.org/wiki/Component_(graph_theory)
|
|
|
|
Finding connected components in graph
|
|
|
|
"""
|
|
|
|
test_graph_1 = {0: [1, 2], 1: [0, 3], 2: [0], 3: [1], 4: [5, 6], 5: [4, 6], 6: [4, 5]}
|
|
|
|
test_graph_2 = {0: [1, 2, 3], 1: [0, 3], 2: [0], 3: [0, 1], 4: [], 5: []}
|
|
|
|
|
|
def dfs(graph: dict, vert: int, visited: list) -> list:
|
|
"""
|
|
Use depth first search to find all vertices
|
|
being in the same component as initial vertex
|
|
>>> dfs(test_graph_1, 0, 5 * [False])
|
|
[0, 1, 3, 2]
|
|
>>> dfs(test_graph_2, 0, 6 * [False])
|
|
[0, 1, 3, 2]
|
|
"""
|
|
|
|
visited[vert] = True
|
|
connected_verts = []
|
|
|
|
for neighbour in graph[vert]:
|
|
if not visited[neighbour]:
|
|
connected_verts += dfs(graph, neighbour, visited)
|
|
|
|
return [vert, *connected_verts]
|
|
|
|
|
|
def connected_components(graph: dict) -> list:
|
|
"""
|
|
This function takes graph as a parameter
|
|
and then returns the list of connected components
|
|
>>> connected_components(test_graph_1)
|
|
[[0, 1, 3, 2], [4, 5, 6]]
|
|
>>> connected_components(test_graph_2)
|
|
[[0, 1, 3, 2], [4], [5]]
|
|
"""
|
|
|
|
graph_size = len(graph)
|
|
visited = graph_size * [False]
|
|
components_list = []
|
|
|
|
for i in range(graph_size):
|
|
if not visited[i]:
|
|
i_connected = dfs(graph, i, visited)
|
|
components_list.append(i_connected)
|
|
|
|
return components_list
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|