题解 | 求二叉树的层序遍历

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型二维数组
#
class Solution:
    def levelOrder(self , root: TreeNode) -> List[List[int]]:
        # write code here
        res=[]
        if not  root:
            return res 
        cur=[root]
        while cur:
            next=[] # 保存下一行
            vals=[] #保存值
            for node in cur:
                vals.append(node.val)
                if node .left:
                    next.append(node.left)
                    
                if node.right:
                    next.append(node.right)
            cur=next
            res.append(vals)
        return res