面试150 二叉树的层序遍历

思路

通过队列去实现即可

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:res=[]que=deque()if root:que.append(root)while que:L=len(que)tmp=[]while L:L-=1node=que.popleft()tmp.append(node.val)if node.left:que.append(node.left)if node.right:que.append(node.right)res.append(tmp)#一层处理完之后return res