Python版本
class UF:
parent = {}
size = {}
cnt = 0
def __init__(self, M):
# 初始化 parent,size 和 cnt
# self.parent = {i for i in range(n)}
def find(self, x):
while x != self.parent[x]:
x = self.parent[x]
self.parent[x] = self.parent[self.parent[x]] # 路径压缩:隔代压缩(基于循环)
return x
# def find(self, x):
# if x != self.parent[x]:
# self.parent[x] = self.find(self.parent[x]) # 路径压缩:完全压缩(基于递归)
# return self.parent[x]
def union(self, p, q):
if self.connected(p, q): return
leader_p = self.find(p) # 小的树挂到大的树上,使树尽量平衡,即按秩合并,基于size的优化方法
leader_q = self.find(q)
if self.size[leader_p] < self.size[leader_q]:
self.parent[leader_p] = leader_q
else:
self.parent[leader_q] = leader_p
self.cnt -= 1
def connected(self, p, q):
return self.find(p) == self.find(q)