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 pRoot TreeNode类

@return int整型二维数组

class Solution: def Print(self , pRoot: TreeNode) -> List[List[int]]: # write code here # 层先输出 res, stk, lv=[], [], 0 if not pRoot: return res stk.append(pRoot) while len(stk) != 0: n = len(stk) tmp =[] for i in range(n): node = stk.pop(0) tmp.append(node.val) if node.left: stk.append(node.left) if node.right: stk.append(node.right) #奇数层反转同一层元素。 if lv % 2 ==1: tmp.reverse() lv += 1 res.append(tmp) return res