[leetcode] 199. Binary Tree Right Side View _ Algorithm Problem Solve for python

1. Problem

199. Binary Tree Right Side View

Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

Example 1:

Input: root = [1,2,3,null,5,null,4]
Output: [1,3,4]

Example 2:

Input: root = [1,null,3]
Output: [1,3]

Example 3:

Input: root = []
Output: []


  • The number of nodes in the tree is in the range [0, 100].
  • -100 <= Node.val <= 100

2. Solution

I solved this problem like this.

  • We can solve this problem to bfs. Using deque!
class Solution:
    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
        ans = []
        if root is None:
            return ans
        deq = deque([root]) 
        while deq:
            nodes = deq.copy()
            for node in nodes:
                if node.left is not None:
                if node.right is not None:

        return ans