[leetcode 133]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;
}
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];

}
};