[LeetCode] 133 Clone Graph

/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> neighbors;
    Node() {
        val = 0;
        neighbors = vector<Node*>();
    }
    Node(int _val) {
        val = _val;
        neighbors = vector<Node*>();
    }
    Node(int _val, vector<Node*> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
};
*/
class Solution {
public:
  std::map<int, Node*> cloneNodeMap;
  Node* cloneGraph(Node* curNode) {
    if (curNode == nullptr)
      return nullptr;
    auto cloneNode = new Node(curNode->val);
    cloneNodeMap[curNode->val] = cloneNode;
    for (Node* neighbor : curNode->neighbors) {
      if (cloneNodeMap[neighbor->val] == nullptr) {
        Node* cloneNeighbor = cloneGraph(neighbor);
        cloneNode->neighbors.push_back(cloneNeighbor);
      }
      else
        cloneNode->neighbors.push_back(cloneNodeMap[neighbor->val]);
    }
    return cloneNode;
  }
};