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45 lines
1.2 KiB
Python
45 lines
1.2 KiB
Python
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# Finding Articulation Points in Undirected Graph
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def computeAP(l):
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n = len(l)
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outEdgeCount = 0
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low = [0] * n
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visited = [False] * n
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isArt = [False] * n
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def dfs(root, at, parent, outEdgeCount):
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if parent == root:
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outEdgeCount += 1
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visited[at] = True
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low[at] = at
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for to in l[at]:
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if to == parent:
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pass
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elif not visited[to]:
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outEdgeCount = dfs(root, to, at, outEdgeCount)
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low[at] = min(low[at], low[to])
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# AP found via bridge
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if at < low[to]:
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isArt[at] = True
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# AP found via cycle
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if at == low[to]:
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isArt[at] = True
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else:
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low[at] = min(low[at], to)
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return outEdgeCount
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for i in range(n):
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if not visited[i]:
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outEdgeCount = 0
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outEdgeCount = dfs(i, i, -1, outEdgeCount)
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isArt[i] = (outEdgeCount > 1)
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for x in range(len(isArt)):
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if isArt[x] == True:
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print(x, end=" ")
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# Adjacency list of graph
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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]}
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computeAP(l)
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