133 Clone Graph - 爱码网

Given a reference of a node in a connected undirected graph, return a deep copy (clone) of the graph. Each node in the graph contains a val (int) and a list (List[Node]) of its neighbors.

Example:

133 Clone Graph

Input:
{"$id":"1","neighbors":[{"$id":"2","neighbors":[{"$ref":"1"},{"$id":"3","neighbors":[{"$ref":"2"},{"$id":"4","neighbors":[{"$ref":"3"},{"$ref":"1"}],"val":4}],"val":3}],"val":2},{"$ref":"4"}],"val":1}

Explanation:
Node 1's value is 1, and it has two neighbors: Node 2 and 4.
Node 2's value is 2, and it has two neighbors: Node 1 and 3.
Node 3's value is 3, and it has two neighbors: Node 2 and 4.
Node 4's value is 4, and it has two neighbors: Node 1 and 3.
 

Note:

The number of nodes will be between 1 and 100.
The undirected graph is a simple graph, which means no repeated edges and no self-loops in the graph.
Since the graph is undirected, if node p has node q as neighbor, then node q must have node p as neighbor too.
You must return the copy of the given node as a reference to the cloned graph.

2 尝试解

class Solution {
public:
    Node* cloneGraph(Node* node) {
        Node* cur = node;
        map<Node*,Node*> link;
        queue<Node*> unvisited;
        unvisited.push(cur);
        while(!unvisited.empty()){
            cur = unvisited.front();
            unvisited.pop();
            if(link.count(cur)==0){
                Node* copy = new Node();  
                copy->val = cur->val;
                link[cur] = copy;
            }
            for(Node* neighbor : cur->neighbors){
                if(link.count(neighbor) == 0){
                    unvisited.push(neighbor);
                }
            }
        }
        map<Node*,Node*>:: iterator eachnode;
        eachnode = link.begin();
        while(eachnode != link.end()){
            for(Node* neighbor : eachnode->first->neighbors){
                eachnode->second->neighbors.push_back(link[neighbor]);
            }
            eachnode++;
        }
        return link[node];
    }
};

3 标准解

class Solution {
public:
    Node* cloneGraph(Node* node) {
        if (!node) {
            return NULL;
        }
        if (copies.find(node) == copies.end()) {
            copies[node] = new Node(node -> val, {});
            for (Node* neighbor : node -> neighbors) {
                copies[node] -> neighbors.push_back(cloneGraph(neighbor));
            }
        }
        return copies[node];
    }
private:
    unordered_map<Node*, Node*> copies;
};