Clone Graph

Clone an undirected graph. Each node in the graph contains a label and a list of itsneighbors.

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#.

1. First node is labeled as 0. Connect node0 to both nodes 1 and2.
2. Second node is labeled as 1. Connect node1 to node 2.
3. Third node is labeled as 2. Connect node2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

       1      / \     /   \    0 --- 2         / \         \_/

Solution:

/** * 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 node;        queue<UndirectedGraphNode*> q;        unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> um;        q.push(node);        UndirectedGraphNode *clone = new UndirectedGraphNode(node->label);        um[node] = clone;        while(!q.empty())        {            UndirectedGraphNode *next = q.front();            q.pop();            for(int i = 0; i < next->neighbors.size(); ++i)            {                if(!um.count(next->neighbors[i]))                {                    UndirectedGraphNode *nb = new UndirectedGraphNode(next->neighbors[i]->label);                    um[next->neighbors[i]] = nb;                    um[next]->neighbors.push_back(nb);                    q.push(next->neighbors[i]);                }                else um[next]->neighbors.push_back(um[next->neighbors[i]]);            }        }        return um[node];    }};