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[LeetCode] Clone Graph

时间:2015-08-16 19:55:36      阅读:149      评论:0      收藏:0      [点我收藏+]

标签:c++   leetcode   

Clone Graph

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

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
         /          \_/

解题思路:

题意为拷贝图。我们可以用一个map来存储新图的标签到节点指针的映射关系。同时,用一个队列来存储待确定邻居的节点(原图节点指针,因为我们通过指针标签很容易找到新图节点指针)。

/**
 * Definition for undirected graph.
 * struct UndirectedGraphNode {
 *     int label;
 *     vector<UndirectedGraphNode *> neighbors;
 *     UndirectedGraphNode(int x) : label(x) {};
 * };
 */
class Solution {
public:
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if(node==NULL){
            return NULL;
        }
        map<int, UndirectedGraphNode*> nodeMap; //存的是新图的标签到节点指针对
        queue<UndirectedGraphNode*> nodeQ;      //存的是原图的节点指针
        
        UndirectedGraphNode* newNode = new UndirectedGraphNode(node->label);
        nodeMap[node->label] = newNode;
        nodeQ.push(node);
        
        while(!nodeQ.empty()){
            UndirectedGraphNode* n = nodeQ.front();
            nodeQ.pop();
            for(int i=0; i<n->neighbors.size(); i++){
                if(nodeMap.find(n->neighbors[i]->label) == nodeMap.end()){
                    nodeMap[n->neighbors[i]->label] = new UndirectedGraphNode(n->neighbors[i]->label);
                    nodeQ.push(n->neighbors[i]);
                }
                nodeMap[n->label]->neighbors.push_back(nodeMap[n->neighbors[i]->label]);
            }
        }
        
        return newNode;
    }
};

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[LeetCode] Clone Graph

标签:c++   leetcode   

原文地址:http://blog.csdn.net/kangrydotnet/article/details/47704051

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