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  • 【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
             / 
             \_/
     1 /**
     2  * Definition for undirected graph.
     3  * struct UndirectedGraphNode {
     4  *     int label;
     5  *     vector<UndirectedGraphNode *> neighbors;
     6  *     UndirectedGraphNode(int x) : label(x) {};
     7  * };
     8  */
     9 class Solution {
    10 public:
    11     UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
    12         unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> map;
    13         if (node == nullptr) {
    14             return nullptr;
    15         }
    16         return clone(node, map);
    17     }
    18 private:
    19     UndirectedGraphNode *clone(UndirectedGraphNode *node, 
    20             unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> &map) {
    21         if (map.find(node) != map.end()) {
    22             return map[node];
    23         } 
    24         UndirectedGraphNode *new_node = new UndirectedGraphNode(node->label);
    25         map[node] = new_node;
    26         for (auto n : node->neighbors) {
    27             new_node->neighbors.push_back(clone(n, map));
    28         }
    29         return new_node;
    30     }
    31 };
    View Code

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  • 原文地址:https://www.cnblogs.com/dengeven/p/3766447.html
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