LintCode 137. 克隆圖

137. 克隆圖
     中文English
     克隆一張無向圖. 無向圖的每個節點包含一個 label 和一個列表 neighbors. 保證每個節點的 label 互不相同.

你的程序需要返回一個經過深度拷貝的新圖. 新圖和原圖具有同樣的結構, 並且對新圖的任何改動不會對原圖造成任何影響.

Example
樣例1

輸入:
{1,2,4#2,1,4#4,1,2}
輸出:
{1,2,4#2,1,4#4,1,2}
解釋:
1------2
\ |
\ |
\ |
\ |
4
Clarification
關於無向圖的表示: http://www.lintcode.com/help/graph/

Notice
你需要返回與給定節點具有相同 label 的那個節點
Python bfs思想

"""
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):
        root = node
        if node is None:
            return node
        
        # use bfs algorithm to traverse the graph and get all nodes
        nodes = self.getNodes(node)
        print("hello")
        # copy node, store the old -> new mapping information in a hash map
        mapping = {}
        for node in nodes:
            mapping[node] = UndirectedGraphNode(node.label)
            
        # copy neighbors(edge)
        for node in nodes:
            new_node = mapping[node]
            for neighbor in node.neighbors:
                new_neighbor = mapping[neighbor]
                new_node.neighbors.append(new_neighbor)
                
        return mapping[root]
    
    
    def getNodes(self, node):
        q = collections.deque([node])
        result = set([node])
        while q:
            head = q.popleft()
            for neighbor in head.neighbors:
                if neighbor not in result:
                    result.add(neighbor)
                    q.append(neighbor)
        return result