[Leetcode] Clone Graph

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

OJ ' s undirected graph serialization:

Nodes is 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 have a total of three nodes, and therefore contains three parts as Separated By # .

2. first node is labeled As 0 . Connect node 0  to both Nodes 1  and 2 .
4. second node is labeled As 1 . Connect node 1  to node 2 .
6. 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         /          \_/

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topic requires copying a diagramAccording to test instructions we find that lable is unique and it marks a node. So we can use the associative container map and use lable as key to save the addresses of the points that have been created.a recursive version is written first:

Class Solution {Public:<span style= "White-space:pre" ></span>undirectedgraphnode *cloneGraph ( Undirectedgraphnode *node) {<span style= "White-space:pre" ></span>if (NULL = = node) return Null;<span Style= "White-space:pre" ></span>map<int, Undirectedgraphnode *> occured;<span style= "White-space: Pre "></span>return Clone (node, occured); <span style=" White-space:pre "></span>}<span style= "White-space:pre" ></span>undirectedgraphnode *clone (Undirectedgraphnode *node, Map<int, Undirectedgraphnode *> &occured) {<span style= "White-space:pre" ></span>if (Occured.count (node- >label) = = 0) {<span style= "white-space:pre" ></span>undirectedgraphnode *newnode = new Undirectedgraphnode (Node->label); <span style= "White-space:pre" ></span>occured[node->label] = Newnode;<span style= "White-space:pre" ></span>for (int i = 0; i < node->neighbors.size (); i++) {< Span style= "White-space:pre "></span>newnode->neighbors.push_back (Clone (node->neighbors[i), occured));< Span style= "White-space:pre" ></span>}<span style= "White-space:pre" ></span>return NewNode; <span style= "White-space:pre" ></span>}<span style= "White-space:pre" ></span>else{<span Style= "White-space:pre" ></span>return occured[node->label];<span style= "White-space:pre" ></ Span>}<span style= "White-space:pre" ></span>}};

and then wrote a non-recursive version, this time with each node in the original address as key, to store the address of the corresponding new nodeuse a queue to save the node you want to access

Class Solution {Public:undirectedgraphnode *clonegraph (Undirectedgraphnode *node) {if (NULL = = node) return null;map< Undirectedgraphnode *, Undirectedgraphnode *> occured;queue<undirectedgraphnode *> visit;visit.push (node); while (!visit.empty ()) {Undirectedgraphnode *cur = Visit.front (); Visit.pop (); if (occured.count (cur) = = 0) { Undirectedgraphnode *newnode = new Undirectedgraphnode (Cur->label); occured[cur] = NewNode;} for (int i = 0; i < cur->neighbors.size (); i++) {Undirectedgraphnode *tmp = cur->neighbors[i];if (Occured.count (tm p) = = 0) {Undirectedgraphnode *newnode = new Undirectedgraphnode (Tmp->label); occured[tmp] = Newnode;visit.push (TMP);} Occured[cur]->neighbors.push_back (Occured[tmp]);}} return occured[node];};

the two-segment code is all over the AC

[Leetcode] Clone Graph