def topo_sort_bfs(g:Graph):
#建立入度表
in_degrees = {}
for v in g:
if v.id not in in_degrees:
in_degrees[v.id] = 0
for nbr in v.getConnections():
in_degrees[nbr.id] = in_degrees.get(nbr.id,0) + 1
# print(in_degrees)
#找起始节点
queue = []
for key,value in in_degrees.items():
if value == 0:
queue.append(key)
#拓扑排序
tuopu = []
while queue:
cur_id = queue.pop(0)
tuopu.append(cur_id)
for nbr in g.getVertex(cur_id).getConnections():
in_degrees[nbr.id] = in_degrees.get(nbr.id) - 1
if in_degrees[nbr.id] == 0:
queue.append(nbr.id)
#返回结果
return tuopu if len(tuopu) == len(g.getVertices()) else []
def topo_sort_dfs(g:Graph):
#找出有入度的节点
in_nodes = set()
for v in g:
for nbr in v.getConnections():
in_nodes.add(nbr.id)
#找出起始节点
start_nodes = []
for node in g.getVertices():
if node not in list(in_nodes):
start_nodes.append(node)
'''
对递归版dfs做点改变
'''
def dfs(node:Vertex,path=''):
if not node.getConnections():
paths.append(path + node.id)
return
for nbr in node.getConnections():
dfs(nbr,path + node.id)
return
paths = []
for node in start_nodes:
dfs(g.getVertex(node))
#打印结果
for str in paths:
for char in str:
print(char,end=' ')
print()
n.setPred(closest)
n.setDistance(newCost)
pq.decreaseKey(n, newCost)
return G
g = Graph()
g.addVertex(0)
g.addVertex(1)
g.addVertex(2)
g.addVertex(3)
g.addEdge(0, 1, 10)
g.addEdge(1, 0, 10)
g.addEdge(0, 2, 6)
g.addEdge(2, 0, 6)
g.addEdge(0, 3, 5)
g.addEdge(3, 0, 5)
g.addEdge(1, 3, 15)
g.addEdge(3, 1, 15)
g.addEdge(2, 3, 4)
g.addEdge(3, 2, 4)
p = prim(g, g.getVertex(0))
for v in p:
if v.getDistance() != sys.maxsize and v.getPred() is not None:
print(
f'src={v.getPred().getId()}, dest={v.getId()}, weight={v.getDistance()}'
)
if new_distance < n.getDistance():
n.setDistance(new_distance)
n.setPred(closest)
# O(E*logV)
pq.decreaseKey(n, new_distance)
g = Graph()
g.addVertex(0)
g.addVertex(1)
g.addVertex(2)
g.addVertex(3)
g.addEdge(0, 1, 10)
g.addEdge(0, 2, 6)
g.addEdge(0, 3, 5)
g.addEdge(1, 3, 15)
g.addEdge(2, 3, 4)
d = dijsktras(g, g.getVertex(0))
print('Distances from {}: '.format(0), end="\n")
print("********************")
for v in d:
print('Distance to {}: {}'.format(v.getId(), d[v]))
print()
d_p = dijkstras_pq(g, g.getVertex(0))
print('Distances from {}: '.format(0), end="\n")
print("********************")
for v in g:
print('Distance to {}: {}'.format(v.getId(), v.getDistance()))
print()
from pythonds import Graph
import timeit
from algorithms import Prims
from Stats import Display
graph = Graph()
Display.creategraph(Display, graph)
v = graph.getVertex(1)
testing = 10
exe = 0
exe2 = 0
# Prim 1
for i in range(testing):
start_time = timeit.default_timer()
Prims.prim1(Prims, graph, v)
time = timeit.default_timer() - start_time
exe += time
average = exe / testing
print("Prim 1 took:", average, 'on average')
'''
# Prim 2
for x in range(testing):
start_time = timeit.default_timer()
Prims.prim2(Prims, graph, v)
time = timeit.default_timer() - start_time
exe2 += time
average = exe2 / testing
print("Prim 2 took:", average, 'on average')
