/**

* Difficulty:

* Medium

*

* Desc:

* 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.

* function UndirectedGraphNode(label) {

* this.label = label;

* this.neighbors = []; // Array of UndirectedGraphNode

* }

*/

/**

* @param {UndirectedGraphNode} graph

* @return {UndirectedGraphNode}

*/

var cloneGraph = function(graph) {

const tmp = {};

if (!graph) return null;

const clone = (node) => {

if (tmp[node.label]) return tmp[node.label];

const c = new UndirectedGraphNode(node.label);

const { neighbors } = node;

for (let i = 0; i < neighbors.length; i += 1) {

const neighbor = neighbors[i];

if (neighbor.label === node.label) {

c.neighbors.push(c);

} else {

c.neighbors.push(clone(neighbor));

}

}

tmp[node.label] = c;

return c;

};

return clone(graph);

};