栈和队列_leetcode199

# 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 rightSideView(self,root):
"""
 :type root: TreeNode
 :rtype: List[int]
 """

 res = []

if not root:
return res

 queue = []
 queue.append(root)

while queue:
 level = []

for i in range(len(queue)):
 node = queue.pop(0)
 level.append(node.val)

if node.left:
 queue.append(node.left)
if node.right:
 queue.append(node.right)

 res.append(level.pop())
return res