assert self.hasPathTo(w), 'There is no path!'
pathlist = [w]
currentVert = self.vertDict[w]
while currentVert != self.startVert:
currentVert = currentVert.getPred()
pathlist.append(currentVert.getId())
pathlist.reverse()
return pathlist
def showPath(self, w):
assert w >= 0 and w < len(self.vertDict)
assert self.hasPathTo(w), 'There is no path!'
pathlist = self.shortestPath(w)
print(pathlist)
g = SparseGraph(directed=True, weighted=True)
buildGraphFromFile(g, 'testDAG.txt')
T = TopologicalSort(g)
DAG = DAGShortestPath(T.getSortedList(), 2)
print(DAG.shortestPathTo(6))
DAG.showPath(6)
'''
这个实现是这样的：
先定义一个类求出DAG的拓扑排序，装在一个list中。
然后再定义一个求DAG最短路径的类，这个类接受一个装载拓扑排序结果的list和源id
这两个类之间没关系，每个类都可以拿出来单独调用。
其实也可以把这两个类的操作合并成一个类，但我懒得考虑如何实现更合理了，反正算法思想已经实现出来了
'''
assert w >= 0 and w < len(self.graph.vertDict)
return self.graph.vertDict[w].visited()
def shortestPath(self, w):
assert w >= 0 and w < len(self.graph.vertDict)
if not self.hasPathTo(w):
return print('There is no path between %s and %s' %
(self.startVert.getId(), w))
pathlist = [w]
currentVert = self.graph.vertDict[w]
while currentVert != self.startVert:
currentVert = currentVert.getPred()
pathlist.append(currentVert.getId())
pathlist.reverse()
return pathlist
def showPath(self, w):
assert w >= 0 and w < len(self.graph.vertDict)
pathlist = self.shortestPath(w)
print(pathlist)
g = SparseGraph(directed=True, weighted=True)
buildGraphFromFile(g, 'testG2.txt')
S = Spfa(g, 0)
print(S.shortestPathTo(4))
S.showPath(4)
'''
对于spfa算法来说，检测是否有负权环的方法是：同一个节点进入队列的次数超过N次(N-1次?)。
这里我偷懒了，没有对图的负权环进行检测，所以不要传入带负权环的图去测试。
'''
class ComponentsCounter(object):
def __init__(self, aGraph):
self.graph = aGraph
self.result = 0
self.calc()
def calc(self): #result store in both graph.ccount and self.result
for vertex in self.graph:
vertex.setVisited(False)
for vertex in self.graph:
if not vertex.visited():
self._dfs(vertex, self.graph.getCcount())
self.graph.setCcount(self.graph.getCcount() + 1)
self.result += 1
def _dfs(self, startVertex, ccount):
startVertex.setCCID(ccount)
startVertex.setVisited(True)
for nextVertex in startVertex.getConnections():
if not nextVertex.visited():
self._dfs(nextVertex, ccount)
def getResult(self):
return self.result
graph = SparseGraph()
buildGraphFromFile(graph, 'testG1.txt')
Counter = ComponentsCounter(graph)
print(Counter.getResult())
print(graph.isConnected(0, 5))