python-leetcode面试题解之第107题二叉树的层序遍历II.zip

# Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): # def levelOrderBottom(self, root): # """ # :type root: TreeNode # :rtype: List[List[int]] # """ # res = [] # if root is None: # return [] # self.get_level(res, root, 0) # # reverse result # res.reverse() # return res # # def get_level(self, res, root, depth): # if root is None: # return # if depth == len(res): # res.append([]) # res[depth].append(root.val) # self.get_level(res, root.left, depth + 1) # self.get_level(res, root.right, depth + 1) def levelOrderBottom(self, root): if root is None: return [] # use stack stack = [[root]] res = [] while len(stack) > 0: top = stack.pop() res.insert(0, [t.val for t in top]) temp = [] for node in top: if node.left is not None: temp.append(node.left) if node.right is not None: temp.append(node.right) if len(temp) > 0: stack.append(temp) return res