剑指 从上到下打印二叉树
从上往下打印二叉树
http://www.nowcoder.com/questionTerminal/7fe2212963db4790b57431d9ed259701
层序遍历 树
import collections class Solution: # 返回从上到下每个节点值列表,例:[1,2,3] def PrintFromTopToBottom(self, root): # write code here queue=collections.deque([root]) visit=[] result=[] if root==None: return result while queue: root=queue.popleft() if root.left: queue.append(root.left) if root.right: queue.append(root.right) if root not in visit: result.append(root.val) visit.append(root) return result