/*
// 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 {
public Node cloneGraph(Node node) {
if (node == null) {
return node;
}
HashMap<Node, Node> visited = new HashMap();
// 将题目给定的节点添加到队列
LinkedList<Node> queue = new LinkedList<Node> ();
queue.add(node);
// 克隆第一个节点并存储到哈希表中
visited.put(node, new Node(node.val, new ArrayList()));
// 广度优先搜索
while (!queue.isEmpty()) {
// 取出队列的头节点
Node n = queue.remove();
// 遍历该节点的邻居
for (Node neighbor: n.neighbors) {
if (!visited.containsKey(neighbor)) {
// 如果没有被访问过,就克隆并存储在哈希表中
visited.put(neighbor, new Node(neighbor.val, new ArrayList()));
// 将邻居节点加入队列中
queue.add(neighbor);
}
// 更新当前节点的邻居列表
visited.get(n).neighbors.add(visited.get(neighbor));
}
}
return visited.get(node);
}
}