题目链接

层序遍历

/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> children;

    public Node() {}

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val, List<Node> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
    public List<List<Integer>> levelOrder(Node root) {
        List<List<Integer>> list = new ArrayList();
        LinkedList<Node> queue = new LinkedList<>();
        if(root != null){
            queue.offer(root);
        }
        while(!queue.isEmpty()){
            List<Integer> list1 = new ArrayList();
            int size = queue.size();
            for(int i = 0; i < size; i++){
                Node node = queue.poll();
                // 与二叉树相比变化代码
                list1.add(node.val);
                if(node.children != null){
                    queue.addAll(node.children);
                }
            }
            list.add(list1);
        }
        return list;
    }
}