[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

#

.

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<UndirectedGraphNode *,UndirectedGraphNode *> nodeMap;
queue<UndirectedGraphNode *> visit;
visit.push(node);
UndirectedGraphNode * copyNode = new UndirectedGraphNode(node -> label);
nodeMap[node] = copyNode;
while(visit.size() > 0){
UndirectedGraphNode *cur = visit.front();
visit.pop();
for(int i = 0;i < cur -> neighbors.size();i ++){
UndirectedGraphNode *neighbor = cur -> neighbors[i];
if(nodeMap.find(neighbor) == nodeMap.end()){
UndirectedGraphNode *neighborCopy = new UndirectedGraphNode(neighbor -> label);
nodeMap[cur] -> neighbors.push_back(neighborCopy);
nodeMap[neighbor] = neighborCopy;
visit.push(neighbor);
}else{
nodeMap[cur] ->neighbors.push_back(nodeMap[neighbor]);
}
}
}
return copyNode;
}
};