python数据结构之图深度优先和广度优先实例详解

#!/usr/bin/python
# -*- coding: utf-8 -*-
class Graph(object):
  def __init__(self,*args,**kwargs):
    self.node_neighbors = {}
    self.visited = {}
  def add_nodes(self,nodelist):
    for node in nodelist:
      self.add_node(node)
  def add_node(self,node):
    if not node in self.nodes():
      self.node_neighbors[node] = []
  def add_edge(self,edge):
    u,v = edge
    if(v not in self.node_neighbors[u]) and ( u not in self.node_neighbors[v]):
      self.node_neighbors[u].append(v)
      if(u!=v):
        self.node_neighbors[v].append(u)
  def nodes(self):
    return self.node_neighbors.keys()
  def depth_first_search(self,root=None):
    order = []
    def dfs(node):
      self.visited[node] = True
      order.append(node)
      for n in self.node_neighbors[node]:
        if not n in self.visited:
          dfs(n)
    if root:
      dfs(root)
    for node in self.nodes():
      if not node in self.visited:
        dfs(node)
    print order
    return order
  def breadth_first_search(self,root=None):
    queue = []
    order = []
    def bfs():
      while len(queue)> 0:
        node = queue.pop(0)
        self.visited[node] = True
        for n in self.node_neighbors[node]:
          if (not n in self.visited) and (not n in queue):
            queue.append(n)
            order.append(n)
    if root:
      queue.append(root)
      order.append(root)
      bfs()
    for node in self.nodes():
      if not node in self.visited:
        queue.append(node)
        order.append(node)
        bfs()
    print order
    return order
if __name__ == '__main__':
  g = Graph()
g.add_nodes([i+1 for i in range(8)])
g.add_edge((1, 2))
g.add_edge((1, 3))
g.add_edge((2, 4))
g.add_edge((2, 5))
g.add_edge((4, 8))
g.add_edge((5, 8))
g.add_edge((3, 6))
g.add_edge((3, 7))
g.add_edge((6, 7))
print "nodes:", g.nodes()
order = g.breadth_first_search(1)
order = g.depth_first_search(1)