def DFS_bridge(g, u, discovered, ordineVisita):
for e in g.incident_edges(u): # for every outgoing edge from u
v = e.opposite(u)
if v not in discovered: # v is an unvisited vertex
newEdge = Graph.Edge(u, v, None)
ordineVisita.append(newEdge)
discovered[v] = e # e is the tree edge that discovered v
DFS_bridge(g, v, discovered,
ordineVisita) # recursively explore from v
def iterative_dfs(starting_vertex, graph):
"""Perform DFS of the undiscovered portion of Graph g starting at Vertex u.
It takes O(sum(degree(v)^2) + V)"""
starting_vertex.discovered = True
starting_vertex.discovery_edge = Graph.Edge(starting_vertex, None,
None) # Dummy edge
walk = starting_vertex
while walk is not None:
has_to_go_back = True
for edge in graph.incident_edges(walk):
opposite = edge.opposite(walk)
if not opposite.discovered:
opposite.discovered = True
opposite.discovery_edge = edge
walk = opposite
has_to_go_back = False
break
if has_to_go_back:
walk = walk.discovery_edge.opposite(walk)
starting_vertex.discovery_edge = None # Remove dummy edge