Find the number connected component in the undirected graph. Each node in the graph contains a label and a list of its neighbors. (a connected component (or just component) of an undirected graph is a subgraph in which any two vertices are connected to each other by paths, and which is connected to no additional vertices in the supergraph.)

Notice

Each connected component should sort by label.

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Clarification

Learn more about representation of graphs

Example

Given graph:

A------B  C
 \     |  | 
  \    |  |
   \   |  |
    \  |  |
      D   E

Return{A,B,D}, {C,E}. Since there are two connected component which is{A,B,D}, {C,E}

bfs, only add node once to queue

/**

* Definition for Undirected graph.

* struct UndirectedGraphNode {

* int label;

* vector<UndirectedGraphNode *> neighbors;

* UndirectedGraphNode(int x) : label(x) {};

* };

*/

class Solution {
public:
/**

 * @param nodes a array of Undirected graph node

 * @return a connected set of a Undirected graph

 */

vector<vector<int>> connectedSet(vector<UndirectedGraphNode*>& nodes) {

    // Write your code here

    vector<vector<int>> res;

    Initialize(nodes);

    unordered_map<UndirectedGraphNode*, vector<int>> sets;

    for (auto& node : nodes) {

        for (auto& next : node->neighbors) {

            Union(node, next);

        }

    }

    for (auto& node : nodes) {

        sets[FindParent(node)].push_back(node->label);

    }

    for (auto nodes : sets) {

        auto& it = nodes.second;

        sort(it.begin(), it.end());

        res.push_back(it);

    }



    return res;

}







unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> mp;

void Initialize(vector<UndirectedGraphNode*>& nodes) {

    for (auto& node : nodes) {

        mp[node] = node;

    }

}

UndirectedGraphNode* FindParent(UndirectedGraphNode* node) {

    while (node != mp[node]) {

        node = mp[node];

    }

    return node;

}



void Union(UndirectedGraphNode* left, UndirectedGraphNode* right) {

    UndirectedGraphNode* pLeft = FindParent(left);

    UndirectedGraphNode* pRight = FindParent(right);

    if (pLeft != pRight) {

        mp[pRight] = pLeft;

    }

}
};