BinaryTreeRightSideView.py

# 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: []
 

# Constraints:

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



# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def rightSideView(self, root: TreeNode) -> List[int]:
        res = []
        q = collections.deque([root])
        
        while q:
            RHS = None
            qLen = len(q)

            for i in range(qLen):
                node = q.popleft()
                if node:
                    RHS = node
                    q.append(node.left)
                    q.append(node.right)
            
            if RHS:
                res.append(RHS.val)

        return res
    

# Runtime 29 ms Beats 98.90%
# Memory 16.2 MB Beats 74.43%