leetcode------Clone Graph

标题：	Clone Graph
通过率：	23.7%
难度：	中等

OJ's undirected graph serialization:

Nodes are labeled uniquely.

We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.

As an example, consider the serialized graph {0,1,2#1,2#2,2}.

The graph has a total of three nodes, and therefore contains three parts as separated by #.

1. First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
2. Second node is labeled as 1. Connect node 1 to node 2.
3. Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

       1
      / 
     /   
    0 --- 2
         / 
         \_/

本题这样出没有什么意义，上面解释一堆再代码里面根本没有显示，直接出图的遍历顺序会好一点。直接看代码

# Definition for a undirected graph node
# class UndirectedGraphNode:
#     def __init__(self, x):
#         self.label = x
#         self.neighbors = []

class Solution:
    # @param node, a undirected graph node
    # @return a undirected graph node
    def cloneGraph(self, node):
        if node == None: return None
        nodeMap={}
        return self.cloneNode(node,nodeMap)
    
    
    def cloneNode(self,node,nodeMap):
        if node == None:return None
        if nodeMap.has_key(node):
            return nodeMap[node]
        else :
            clone =UndirectedGraphNode(node.label)
            nodeMap[node]=clone
            for nei in node.neighbors:
                clone.neighbors.append(self.cloneNode(nei,nodeMap))
        return clone