-
Notifications
You must be signed in to change notification settings - Fork 0
/
Critical_Connections_in_a_Network.py
45 lines (44 loc) · 1.53 KB
/
Critical_Connections_in_a_Network.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
def criticalConnections(self, n: int, connections: List[List[int]]) -> List[List[int]]:
N = []
arr = []
for i in range(n):
N.append([])
arr.append(0)
for i in connections:
N[i[0]].append(i[1])
N[i[1]].append(i[0])
#DFS
index = 0
stack = [[0,0]]
arr[0] = 1
edges = []
while stack:
a,b = stack[-1][0],stack[-1][1]
L = len(N[a])
if b >= L:
if edges and edges[index - 1][1] == a:
index -= 1
stack.pop()
if stack:
stack[-1][1] += 1
else:
if arr[N[a][b]] == 0:
stack.append([N[a][b],0])
arr[N[a][b]] = 1
edges.insert(index,[a,N[a][b]])
index += 1
elif arr[N[a][b]] == 1:
if N[a][b] != stack[-2][0]:
i = -1
index -= 1
while stack[i][0] != N[a][b]:
if len(edges) == 0:
break
if edges[index][1] == stack[i][0]:
edges.pop(index)
index -= 1
i -= 1
index += 1
N[N[a][b]].remove(a)
stack[-1][1] += 1
return edges