在不使用PDP包的情况下,您可以手动创建一个偏依赖图来解决问题。下面是一个包含代码示例的解决方法:
class DependencyGraph:
def __init__(self):
self.dependencies = {}
def add_dependency(self, item, dependency):
if item in self.dependencies:
self.dependencies[item].append(dependency)
else:
self.dependencies[item] = [dependency]
def has_cycle(self, item, visited=None, stack=None):
if visited is None:
visited = set()
if stack is None:
stack = set()
visited.add(item)
stack.add(item)
if item in self.dependencies:
for dependency in self.dependencies[item]:
if dependency not in visited:
if self.has_cycle(dependency, visited, stack):
return True
elif dependency in stack:
return True
stack.remove(item)
return False
def print_graph(self):
for item, dependencies in self.dependencies.items():
print(f"{item} depends on: {', '.join(dependencies)}")
下面是一个完整的示例,演示了如何使用上述代码来创建偏依赖图、添加依赖关系、检测循环依赖并打印图:
class DependencyGraph:
def __init__(self):
self.dependencies = {}
def add_dependency(self, item, dependency):
if item in self.dependencies:
self.dependencies[item].append(dependency)
else:
self.dependencies[item] = [dependency]
def has_cycle(self, item, visited=None, stack=None):
if visited is None:
visited = set()
if stack is None:
stack = set()
visited.add(item)
stack.add(item)
if item in self.dependencies:
for dependency in self.dependencies[item]:
if dependency not in visited:
if self.has_cycle(dependency, visited, stack):
return True
elif dependency in stack:
return True
stack.remove(item)
return False
def print_graph(self):
for item, dependencies in self.dependencies.items():
print(f"{item} depends on: {', '.join(dependencies)}")
# 创建一个偏依赖图对象
graph = DependencyGraph()
# 添加依赖关系
graph.add_dependency('A', 'B')
graph.add_dependency('B', 'C')
graph.add_dependency('C', 'A')
# 检测是否存在循环依赖
if graph.has_cycle('A'):
print("Graph contains cycle")
else:
print("Graph does not contain cycle")
# 打印偏依赖图
graph.print_graph()
在上述示例中,我们首先创建了一个偏依赖图对象 graph
。然后,我们使用 add_dependency
方法添加了一系列依赖关系。接下来,我们使用 has_cycle
方法检测是否存在循环依赖,如果存在则打印 "Graph contains cycle",否则打印 "Graph does not contain cycle"。最后,我们使用 print_graph
方法打印偏依赖图。