mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-05 02:40:16 +00:00
1f5134b368
* Create alternate_disjoint_set.py This code implements a disjoint set using Lists with added heuristics for efficiency Union by Rank Heuristic and Path Compression * Update alternate_disjoint_set.py Added typehints, doctests and some suggested variable name change * Update alternate_disjoint_set.py * Formatted with Black * More formatting * Formatting on line 28 * Error in Doctest * Doctest Update in alternate disjoint set * Fixed build error * Fixed doctest
69 lines
2.1 KiB
Python
69 lines
2.1 KiB
Python
"""
|
|
Implements a disjoint set using Lists and some added heuristics for efficiency
|
|
Union by Rank Heuristic and Path Compression
|
|
"""
|
|
|
|
|
|
class DisjointSet:
|
|
def __init__(self, set_counts: list) -> None:
|
|
"""
|
|
Initialize with a list of the number of items in each set
|
|
and with rank = 1 for each set
|
|
"""
|
|
self.set_counts = set_counts
|
|
self.max_set = max(set_counts)
|
|
num_sets = len(set_counts)
|
|
self.ranks = [1] * num_sets
|
|
self.parents = list(range(num_sets))
|
|
|
|
def merge(self, src: int, dst: int) -> bool:
|
|
"""
|
|
Merge two sets together using Union by rank heuristic
|
|
Return True if successful
|
|
Merge two disjoint sets
|
|
>>> A = DisjointSet([1, 1, 1])
|
|
>>> A.merge(1, 2)
|
|
True
|
|
>>> A.merge(0, 2)
|
|
True
|
|
>>> A.merge(0, 1)
|
|
False
|
|
"""
|
|
src_parent = self.get_parent(src)
|
|
dst_parent = self.get_parent(dst)
|
|
|
|
if src_parent == dst_parent:
|
|
return False
|
|
|
|
if self.ranks[dst_parent] >= self.ranks[src_parent]:
|
|
self.set_counts[dst_parent] += self.set_counts[src_parent]
|
|
self.set_counts[src_parent] = 0
|
|
self.parents[src_parent] = dst_parent
|
|
if self.ranks[dst_parent] == self.ranks[src_parent]:
|
|
self.ranks[dst_parent] += 1
|
|
joined_set_size = self.set_counts[dst_parent]
|
|
else:
|
|
self.set_counts[src_parent] += self.set_counts[dst_parent]
|
|
self.set_counts[dst_parent] = 0
|
|
self.parents[dst_parent] = src_parent
|
|
joined_set_size = self.set_counts[src_parent]
|
|
|
|
self.max_set = max(self.max_set, joined_set_size)
|
|
return True
|
|
|
|
def get_parent(self, disj_set: int) -> int:
|
|
"""
|
|
Find the Parent of a given set
|
|
>>> A = DisjointSet([1, 1, 1])
|
|
>>> A.merge(1, 2)
|
|
True
|
|
>>> A.get_parent(0)
|
|
0
|
|
>>> A.get_parent(1)
|
|
2
|
|
"""
|
|
if self.parents[disj_set] == disj_set:
|
|
return disj_set
|
|
self.parents[disj_set] = self.get_parent(self.parents[disj_set])
|
|
return self.parents[disj_set]
|