leetcode_c++:图：Clone Graph(133)

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
         / \
         \_/

---

算法

DFS

---

#include
#include
#include
#include

using namespace std;

// 无向图
struct UndirectedGraphNode{
    int label;
    vector neighbors;
    UndirectedGraphNode(int x):label(x) {};
};

typedef unordered_map<int, UndirectedGraphNode*> immap;

class Solution {
private:
    immap gmap;

    UndirectedGraphNode* dfs(UndirectedGraphNode* node){
        UndirectedGraphNode* newnode;
        if(gmap.find(node->label)==gmap.end()){
            newnode=new UndirectedGraphNode(node->label);
            gmap.insert(immap::value_type(node->label,newnode));
            for(auto &i:node->neighbors)
                newnode->neighbors.push_back(dfs(i));
        }else{
            newnode=gmap[node->label];
        }

        return newnode;
    }


public:
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {

        if(!node)
            return NULL;
        gmap.clear();
        UndirectedGraphNode* ret=dfs(node);
        return ret;
    }
};

int main(){
    Solution s;
    UndirectedGraphNode* a=new UndirectedGraphNode(0),*b;
    b=s.cloneGraph(a);
    return 0;
}

---

class Solution {
public:
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if (node == NULL) return NULL;

        //create a map, key is source node, value is clone node.
        map cloneMap;

        //using queue for breadth first search
        queue q;
        q.push(node);

        //clone the root
        UndirectedGraphNode* cloneNode = new UndirectedGraphNode(node->label);
        cloneMap[node] = cloneNode;

        //breadth first search
        while(!q.empty()){
            UndirectedGraphNode* n = q.front();
            q.pop();
            //for each neighbors
            for(int i=0; ineighbors.size(); i++){
                UndirectedGraphNode* neighbor= n->neighbors[i];
                //not existed in cloneMap
                if (cloneMap.find(neighbor)==cloneMap.end()){
                    //clone a node
                    UndirectedGraphNode* newNode = new UndirectedGraphNode(neighbor->label);
                    cloneMap[n]->neighbors.push_back(newNode);
                    cloneMap[neighbor] = newNode;

                    //put the neighbors into the queue
                    q.push(neighbor);
                }else{
                    cloneMap[n]->neighbors.push_back(cloneMap[neighbor]);
                }
            }
        }

        return cloneNode;
    }
};