Python/Graphs/finding_bridges.py
Reshad Hasan 9a44eb4479 Organize graph algorithms (#719)
* organized graph algorithms

* all graph algorithms in Graphs/ folder

* all graph algorithms are in one folder

* Rename number theory/factorial_python.py to maths/factorial_python.py
2019-02-25 17:35:24 +08:00

32 lines
909 B
Python

# Finding Bridges in Undirected Graph
def computeBridges(l):
id = 0
n = len(l) # No of vertices in graph
low = [0] * n
visited = [False] * n
def dfs(at, parent, bridges, id):
visited[at] = True
low[at] = id
id += 1
for to in l[at]:
if to == parent:
pass
elif not visited[to]:
dfs(to, at, bridges, id)
low[at] = min(low[at], low[to])
if at < low[to]:
bridges.append([at, to])
else:
# This edge is a back edge and cannot be a bridge
low[at] = min(low[at], to)
bridges = []
for i in range(n):
if (not visited[i]):
dfs(i, -1, bridges, id)
print(bridges)
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]}
computeBridges(l)