[leetcode 133]Clone Graph

最新推荐文章于 2025-12-28 22:03:12 发布

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本文详细介绍了如何使用特定的算法将无向图进行克隆。包括节点的唯一编号、节点之间的连接关系以及实现这一过程的具体步骤。通过实例演示，帮助读者理解并掌握无向图克隆的基本原理。

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 #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
Second node is labeled as 1. Connect node 1 to node 2.
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:

/**
 * 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 *> nodes;
        queue<UndirectedGraphNode*> q;
        q.push(node);
        while (!q.empty()) {
            UndirectedGraphNode *tmp = q.front();
            q.pop();
            if (nodes.find(tmp->label) == nodes.end()) {
                UndirectedGraphNode *newNode = new UndirectedGraphNode(tmp->label);
                nodes.insert(pair<int,UndirectedGraphNode*>(tmp->label,newNode));
                for (auto i = 0; i < tmp->neighbors.size(); i++) {
                    q.push(tmp->neighbors[i]);
                }
            }
        }
        q.push(node);
        while(!q.empty()) {
            UndirectedGraphNode* tmp = q.front();
            q.pop();
            UndirectedGraphNode* tmp2 = nodes[tmp->label];
            if  (tmp2->neighbors.empty() && !tmp->neighbors.empty()) {
                for (auto i = 0; i < tmp->neighbors.size(); i ++) {
                    tmp2->neighbors.push_back(nodes[tmp->neighbors[i]->label]);
                    q.push(tmp->neighbors[i]);
                }
            }
        }
        return nodes[node->label];
        
    }
};