帮我写一个弦图的python的代码
时间: 2023-08-20 17:38:27 浏览: 81
以下是一个简单的弦图Python代码:
```python
class ChordalGraph:
def __init__(self, n):
self.adj = [[] for _ in range(n)]
self.visited = [False] * n
self.parent = [-1] * n
self.color = [None] * n
self.is_chordal = True
self.cliques = []
def add_edge(self, u, v):
self.adj[u].append(v)
self.adj[v].append(u)
def dfs(self, u, order):
self.visited[u] = True
for v in self.adj[u]:
if not self.visited[v]:
self.parent[v] = u
self.dfs(v, order)
order.append(u)
def check_chordal(self):
order = []
for u in range(len(self.adj)):
if not self.visited[u]:
self.dfs(u, order)
order.reverse()
self.color[order[0]] = 0
for u in order:
neighbors = [v for v in self.adj[u] if self.color[v] is not None]
if neighbors:
c = set(self.color[v] for v in neighbors)
if len(c) > 1:
self.is_chordal = False
break
self.color[u] = c.pop()
else:
self.color[u] = max(self.color) + 1
if self.is_chordal:
self.find_maximal_cliques()
def find_maximal_cliques(self):
remaining = set(range(len(self.adj)))
while remaining:
v = remaining.pop()
neighbors = set(self.adj[v]) & remaining
clique = {v} | neighbors
while True:
new_neighbors = set()
for u in neighbors:
new_neighbors |= set(self.adj[u])
new_neighbors -= clique
if not new_neighbors:
break
neighbors |= new_neighbors
clique |= new_neighbors
self.cliques.append(clique)
remaining -= clique
# Example usage
graph = ChordalGraph(5)
graph.add_edge(0, 1)
graph.add_edge(1, 2)
graph.add_edge(2, 3)
graph.add_edge(3, 4)
graph.check_chordal()
print(graph.is_chordal)
print(graph.cliques)
```
这个代码定义了一个`ChordalGraph`的类,它包含了添加边、判断是否是弦图、寻找最大团等方法。在上面的例子中,我们创建了一个5个顶点的图,并添加了一些边,然后检查它是否是弦图,最后输出了是否是弦图和最大团。