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()
