python leetcode 199. Binary Tree Right Side View

层次遍历取最右

class Solution(object):
    def rightSideView(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """ 
        if not root:
            return []
        stack=[root]
        res=[]
        while stack:
            
            stack1=[]
            while stack:
                node=stack.pop()
                stack1.append(node) 
            res.append(stack1[-1].val)
            while stack1:
                node=stack1.pop()
                if node.right:
                    stack.append(node.right)
                if node.left:
                    stack.append(node.left) 
        return res