133. Clone Graph

[namespace-io]

这个题目做的很晕，可能状态不好
思路：
考虑bfs，队列中为要拷贝的Node，遍历其邻居，如果邻居已经被访问，其地址已经被存到map中，加入其拷贝地址即可，如果不在map中，则生产一个地址加入map，同时需要注意的是每次加入队列中的都是未被访问的

dfs也是一样的原理，未访问过的就在map生成一个地址，并且进行递归

/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> neighbors;

    Node() {}

    Node(int _val, vector<Node*> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
};
*/
class Solution {
public:
    unordered_map<Node*, Node*> m;
    unordered_set<Node*> f;
    Node* cloneGraph(Node* node) {
        if(node == nullptr) return nullptr;
    
        queue<Node*> q;
        Node* a, *h;
        a = new Node();
        a->val = node->val;
        m[node] = a;
        q.push(node);
        
        while(!q.empty()){
            int n = q.size();
            for(int i = 0; i < n; i++){
                auto t = q.front();
                q.pop();
                auto c = m[t];
                
                for(int j = 0; j < t->neighbors.size(); j++){
                    if(m.count(t->neighbors[j]) == 0){
                        auto x = new Node();
                        x->val = t->neighbors[j]->val;
                        m[t->neighbors[j]] = x;
                        q.push(t->neighbors[j]);
                    }
                    c->neighbors.push_back(m[t->neighbors[j]]);
                }
               
            }
        }
        
        return m[node];
    }
};

dfs

/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> neighbors;

    Node() {}

    Node(int _val, vector<Node*> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
};
*/
class Solution {
public:
    unordered_map<Node*, Node*> m;
    void dfs(Node* h){
        for(int i = 0; i < h->neighbors.size(); i++){
            if(m.count(h->neighbors[i]) == 0){
                auto x = new Node();
                x->val = h->neighbors[i]->val;
                m[h->neighbors[i]] = x;
                dfs(h->neighbors[i]);
            }
            m[h]->neighbors.push_back(m[h->neighbors[i]]);
        }
    }
    Node* cloneGraph(Node* node) {
        if(node == nullptr) return nullptr;
        Node* a;
        a = new Node();
        a->val = node->val;
        m[node] = a;
        dfs(node);
        
        return m[node];
    }
};