题解 | #求二叉树的层序遍历#
求二叉树的层序遍历
https://www.nowcoder.com/practice/04a5560e43e24e9db4595865dc9c63a3
# 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]]: if not root: return [] lay = [[root]] # 按层存入 res = [] # 存放结果 while lay: now_lay = lay.pop(0) # 当前遍历的层 now_lay_res = [] next_lay = [] # 下一层的节点 for tmp in now_lay: if tmp: now_lay_res.append(tmp.val) if tmp.left: next_lay.append(tmp.left) if tmp.right: next_lay.append(tmp.right) if next_lay: # 如果有元素,存入lay lay.append(next_lay) res.append(now_lay_res) return res