day61（1.20）——leetcode面试经典150

133. 克隆图

133.克隆图

题目：

题解：

/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> neighbors;
    public Node() {
        val = 0;
        neighbors = new ArrayList<Node>();
    }
    public Node(int _val) {
        val = _val;
        neighbors = new ArrayList<Node>();
    }
    public Node(int _val, ArrayList<Node> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
}
*/

class Solution {
    private HashMap<Node, Node> map = new HashMap<>();
    public Node cloneGraph(Node node) {
        if(node == null){
            return null;
        }

        if(map.containsKey(node)) {
            return map.get(node);
        }

        //创建新节点
        Node clone = new Node(node.val);
        //进行映射
        map.put(node, clone);

        //递归所有邻居
        for(Node neighbor : node.neighbors) {
            clone.neighbors.add(cloneGraph(neighbor));
        }
        
        //返回clone
        return clone;

    }
}