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: []

 

Constraints:

  • The number of nodes in the tree is in the range [0, 100].
  • -100 <= Node.val <= 100
SOLUTION:
# 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 getHeight(self, root):
        if root:
            return 1 + max(self.getHeight(root.left), self.getHeight(root.right))
        return 0
    
    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
        h = self.getHeight(root)
        cols = (1 << h) - 1
        res = [(None, float('-inf'))] * h
        nodes = [(root, 0, 0, cols)]
        while len(nodes) > 0:
            curr, l, a, b = nodes.pop()
            if curr:
                i = (a + b) // 2
                if i > res[l][1]:
                    res[l] = (curr.val, i)
                nodes.append((curr.left, l + 1, a, i))
                nodes.append((curr.right, l + 1, i, b))
        return [r[0] for r in res]

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