mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-12-05 02:40:16 +00:00
45 lines
1.2 KiB
Python
45 lines
1.2 KiB
Python
|
# Finding Articulation Points in Undirected Graph
|
||
|
def computeAP(l):
|
||
|
n = len(l)
|
||
|
outEdgeCount = 0
|
||
|
low = [0] * n
|
||
|
visited = [False] * n
|
||
|
isArt = [False] * n
|
||
|
|
||
|
def dfs(root, at, parent, outEdgeCount):
|
||
|
if parent == root:
|
||
|
outEdgeCount += 1
|
||
|
visited[at] = True
|
||
|
low[at] = at
|
||
|
|
||
|
for to in l[at]:
|
||
|
if to == parent:
|
||
|
pass
|
||
|
elif not visited[to]:
|
||
|
outEdgeCount = dfs(root, to, at, outEdgeCount)
|
||
|
low[at] = min(low[at], low[to])
|
||
|
|
||
|
# AP found via bridge
|
||
|
if at < low[to]:
|
||
|
isArt[at] = True
|
||
|
# AP found via cycle
|
||
|
if at == low[to]:
|
||
|
isArt[at] = True
|
||
|
else:
|
||
|
low[at] = min(low[at], to)
|
||
|
return outEdgeCount
|
||
|
|
||
|
for i in range(n):
|
||
|
if not visited[i]:
|
||
|
outEdgeCount = 0
|
||
|
outEdgeCount = dfs(i, i, -1, outEdgeCount)
|
||
|
isArt[i] = (outEdgeCount > 1)
|
||
|
|
||
|
for x in range(len(isArt)):
|
||
|
if isArt[x] == True:
|
||
|
print(x)
|
||
|
|
||
|
# Adjacency list of graph
|
||
|
l = {0:[1,2], 1:[0,2], 2:[0,1,3,5], 3:[2,4], 4:[3], 5:[2,6,8], 6:[5,7], 7:[6,8], 8:[5,7]}
|
||
|
computeAP(l)
|