mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-30 16:31:08 +00:00
bc8df6de31
* [pre-commit.ci] pre-commit autoupdate updates: - [github.com/astral-sh/ruff-pre-commit: v0.2.2 → v0.3.2](https://github.com/astral-sh/ruff-pre-commit/compare/v0.2.2...v0.3.2) - [github.com/pre-commit/mirrors-mypy: v1.8.0 → v1.9.0](https://github.com/pre-commit/mirrors-mypy/compare/v1.8.0...v1.9.0) * [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>
86 lines
1.9 KiB
Python
86 lines
1.9 KiB
Python
"""
|
|
Disjoint set.
|
|
Reference: https://en.wikipedia.org/wiki/Disjoint-set_data_structure
|
|
"""
|
|
|
|
|
|
class Node:
|
|
def __init__(self, data: int) -> None:
|
|
self.data = data
|
|
self.rank: int
|
|
self.parent: Node
|
|
|
|
|
|
def make_set(x: Node) -> None:
|
|
"""
|
|
Make x as a set.
|
|
"""
|
|
# rank is the distance from x to its' parent
|
|
# root's rank is 0
|
|
x.rank = 0
|
|
x.parent = x
|
|
|
|
|
|
def union_set(x: Node, y: Node) -> None:
|
|
"""
|
|
Union of two sets.
|
|
set with bigger rank should be parent, so that the
|
|
disjoint set tree will be more flat.
|
|
"""
|
|
x, y = find_set(x), find_set(y)
|
|
if x == y:
|
|
return
|
|
|
|
elif x.rank > y.rank:
|
|
y.parent = x
|
|
else:
|
|
x.parent = y
|
|
if x.rank == y.rank:
|
|
y.rank += 1
|
|
|
|
|
|
def find_set(x: Node) -> Node:
|
|
"""
|
|
Return the parent of x
|
|
"""
|
|
if x != x.parent:
|
|
x.parent = find_set(x.parent)
|
|
return x.parent
|
|
|
|
|
|
def find_python_set(node: Node) -> set:
|
|
"""
|
|
Return a Python Standard Library set that contains i.
|
|
"""
|
|
sets = ({0, 1, 2}, {3, 4, 5})
|
|
for s in sets:
|
|
if node.data in s:
|
|
return s
|
|
msg = f"{node.data} is not in {sets}"
|
|
raise ValueError(msg)
|
|
|
|
|
|
def test_disjoint_set() -> None:
|
|
"""
|
|
>>> test_disjoint_set()
|
|
"""
|
|
vertex = [Node(i) for i in range(6)]
|
|
for v in vertex:
|
|
make_set(v)
|
|
|
|
union_set(vertex[0], vertex[1])
|
|
union_set(vertex[1], vertex[2])
|
|
union_set(vertex[3], vertex[4])
|
|
union_set(vertex[3], vertex[5])
|
|
|
|
for node0 in vertex:
|
|
for node1 in vertex:
|
|
if find_python_set(node0).isdisjoint(find_python_set(node1)):
|
|
assert find_set(node0) != find_set(node1)
|
|
else:
|
|
assert find_set(node0) == find_set(node1)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
test_disjoint_set()
|