def biconnectivity(G):
depth = [-1] * G.order
cutPoints = [0] * G.order
cutEdges = []
comp = []
st = stack.Stack()
for x in range(G.order):
if depth[x] == -1:
depth[x] = 0
nbChildren = 0
for y in G.adjlists[x]:
if depth[y] == -1:
nbChildren += 1
st.push((x, y))
depth[y] = 1
ph_y = __biconnectivity(G, y, x, depth, cutPoints,
cutEdges, st, comp)
if ph_y > 0: # depth[x]
cutEdges.append((x, y))
bc = []
while not st.isempty():
bc.append(st.pop())
comp.append(bc)
cutPoints[x] += nbChildren - 1
return (cutPoints, cutEdges, comp)
def topologicalOrder(G, src):
'''
make topological order of subgraph from vertices
that are reachable from src
'''
M = [False] * G.order
order = stack.Stack()
dfsSuff(G, src, M, order)
return order
def Tarjan(G):
pref = [0] * G.order
cpt = 0
vertexStack = stack.Stack()
k = 0
cfc = [0] * G.order
for s in range(G.order):
if pref[s] == 0:
(_, cpt, k) = __Tarjan(G, s, pref, cpt, cfc, k, vertexStack)
return (k, cfc )
def eval_rpn(L):
"""
algo:
init pile
pour chaque élément e de L:
si e est une valeur:
l'empiler
sinon #opérateur
évaluation:
récupérer les 2 opérandes = dépiler
empiler le résultat de l'opération
"""
p = stack.Stack()
for e in L:
#FIXME
pass
def Kosaraju(G):
post = stack.Stack()
M = [False] * G.order
for s in range(G.order):
if not M[s]:
__dfsPost(G, s, M, post)
G_1 = reverseGraph(G)
comp = [0]*G.order
no = 0
while not post.isEmpty():
s = post.pop()
if comp[s] == 0:
no += 1
__dfs(G_1, s, comp, no)
return (no, comp)
# -*- coding: utf-8 -*- """ Sept. 2019 @author: nathalie S2# tutorial: to see how to use stacks """ from algopy import stack # a new stack p = stack.Stack() # all operation are implemented as method! # stack.push (empiler) p.push(1) p.push(2) p.push(3) # stack.peek (sommet) print(p.peek()) # stack.pop (sommet + dépiler) print(p.pop()) print(p.peek()) # stack.isempty (est-vide) print(p.isempty()) p.pop() p.pop() print(p.isempty())