题目:原题链接(中等)
标签:树、图、图-无向图、并查集
解法 | 时间复杂度 | 空间复杂度 | 执行用时 |
Ans 1 (Python) | O(N) | O(N) | 124ms (8.02%) |
Ans 2 (Python) | O(N) | O(N) | 72ms (64.08%) |
Ans 3 (Python) |
解法一(集合列表):
class Solution:
def findRedundantConnection(self, edges: List[List[int]]) -> List[int]:
visited_group = []
for edge in edges:
group0, group1 = None, None
for group in visited_group:
if edge[0] in group:
group0 = group
if edge[1] in group:
group1 = group
if group0 and group1:
if group0 == group1:
return edge
else:
visited_group.remove(group0)
visited_group.remove(group1)
visited_group.append(group0 | group1)
elif group0:
group0.add(edge[1])
elif group1:
group1.add(edge[0])
else:
visited_group.append({edge[0], edge[1]})
解法二(并查集):
class DSU:
def __init__(self, n):
self.array = [i for i in range(n)]
self.size = [1] * n
def find(self, i):
if self.array[i] != i:
self.array[i] = self.find(self.array[i])
return self.array[i]
def union(self, i, j):
i = self.find(i)
j = self.find(j)
if self.size[i] >= self.size[j]:
self.array[j] = i
self.size[i] += self.size[j]
else:
self.array[i] = j
self.size[j] += self.size[i]
class Solution:
def findRedundantConnection(self, edges: List[List[int]]) -> List[int]:
dsu = DSU(len(edges)) # 构造并查集实例
for edge in edges:
if dsu.find(edge[0] - 1) == dsu.find(edge[1] - 1):
return edge
else:
dsu.union(edge[0] - 1, edge[1] - 1)