Leetcode 102 : 二叉树的层序遍历

https://leetcode-cn.com/problems/binary-tree-level-order-traversal/submissions/

考察点： 二叉树层次遍历、层次遍历中处理每层数据

import BasicDataStruct.TreeNode;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

public class Leetcode102MiddleOrderSearch {

    public static List<List<Integer>> inorderTraversal(TreeNode root) {

        List<List<Integer>> list = new ArrayList<>();
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            List<Integer> subList = new ArrayList<>();
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                subList.add(node.getVal());
                if (node.left != null) {
                    queue.add(node.left);
                }
                if (node.right != null) {
                    queue.add(node.right);
                }
            }
            list.add(subList);
        }
        return list;
    }


    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);
        root.left = new TreeNode(2);
        root.right = new TreeNode(3);
        root.left.left = new TreeNode(4);
        root.left.right = new TreeNode(5);
        root.right.left = new TreeNode(6);
        root.right.right = new TreeNode(7);
        System.out.println(inorderTraversal(root).toString());
    }

}