[LeetCode Python3] 199. Binary Tree Right Side View +层次遍历

199. Binary Tree Right Side View

该题的本质还是层次遍历，只不过仅把每层的最右边元素记录下来

solution:

class Solution:
    def rightSideView(self, root: TreeNode) -> List[int]:
        if not root:
            return []
        que = [root]
        que1 = []
        res = []
        while que:
            res.append(que[-1].val) # 记录每层最右边的元素
            for tmp in que:
                if tmp.left:
                    que1.append(tmp.left)
                if tmp.right:
                    que1.append(tmp.right)
            que = que1[:]
            que1.clear()
        return res