Leetcode 133. Clone Graph (Medium) (cpp)

Leetcode 133. Clone Graph (Medium) (cpp)

Tag: Depth-first Search, Breadth-first Search, Graph

Difficulty: Medium

/*133. Clone Graph (Medium)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:1/ \/   \0 --- 2/ \\_/*//*** 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;}unordered_map<int, UndirectedGraphNode*> mapping;UndirectedGraphNode *newhead = new UndirectedGraphNode(node->label);mapping[node->label] = newhead;queue<UndirectedGraphNode*> q;q.push(node);while (!q.empty()) {UndirectedGraphNode *node1 = q.front();q.pop();for (UndirectedGraphNode* nei : node1->neighbors) {if (mapping.find(nei->label) == mapping.end()) {mapping[nei->label] = new UndirectedGraphNode(nei->label);q.push(nei);}mapping[node1->label]->neighbors.push_back(mapping[nei->label]);}}return newhead;}};