mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-24 13:31:07 +00:00
83b825027e
* graphs/kruskal: add doctest & type hints this is a child of a previous PR #2443 its ancestor is #2128 * updating DIRECTORY.md * graphs/kruskal: fix max-line-length violation * fixup! Format Python code with psf/black push Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
48 lines
1.4 KiB
Python
48 lines
1.4 KiB
Python
from typing import List, Tuple
|
|
|
|
|
|
def kruskal(num_nodes: int, num_edges: int, edges: List[Tuple[int, int, int]]) -> int:
|
|
"""
|
|
>>> kruskal(4, 3, [(0, 1, 3), (1, 2, 5), (2, 3, 1)])
|
|
[(2, 3, 1), (0, 1, 3), (1, 2, 5)]
|
|
|
|
>>> kruskal(4, 5, [(0, 1, 3), (1, 2, 5), (2, 3, 1), (0, 2, 1), (0, 3, 2)])
|
|
[(2, 3, 1), (0, 2, 1), (0, 1, 3)]
|
|
|
|
>>> kruskal(4, 6, [(0, 1, 3), (1, 2, 5), (2, 3, 1), (0, 2, 1), (0, 3, 2),
|
|
... (2, 1, 1)])
|
|
[(2, 3, 1), (0, 2, 1), (2, 1, 1)]
|
|
"""
|
|
edges = sorted(edges, key=lambda edge: edge[2])
|
|
|
|
parent = list(range(num_nodes))
|
|
|
|
def find_parent(i):
|
|
if i != parent[i]:
|
|
parent[i] = find_parent(parent[i])
|
|
return parent[i]
|
|
|
|
minimum_spanning_tree_cost = 0
|
|
minimum_spanning_tree = []
|
|
|
|
for edge in edges:
|
|
parent_a = find_parent(edge[0])
|
|
parent_b = find_parent(edge[1])
|
|
if parent_a != parent_b:
|
|
minimum_spanning_tree_cost += edge[2]
|
|
minimum_spanning_tree.append(edge)
|
|
parent[parent_a] = parent_b
|
|
|
|
return minimum_spanning_tree
|
|
|
|
|
|
if __name__ == "__main__": # pragma: no cover
|
|
num_nodes, num_edges = list(map(int, input().strip().split()))
|
|
edges = []
|
|
|
|
for _ in range(num_edges):
|
|
node1, node2, cost = [int(x) for x in input().strip().split()]
|
|
edges.append((node1, node2, cost))
|
|
|
|
kruskal(num_nodes, num_edges, edges)
|