Range Sum of BST.py

from typing import Optional


class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right


class Solution:
    """
    Time:   O(n)
    Memory: O(n)
    """

    def rangeSumBST(self, root: Optional[TreeNode], low: int, high: int) -> int:
        if root is None:
            return 0
        return self.rangeSumBST(root.left,  low, high) + \
               self.rangeSumBST(root.right, low, high) + \
               root.val * (low <= root.val <= high)


class Solution:
    """
    Time:   O(n)
    Memory: O(n)
    """

    def rangeSumBST(self, root: TreeNode, low: int, high: int) -> int:
        queue = [root]
        range_sum = 0

        while queue:
            node = queue.pop()
            if low <= node.val <= high:
                range_sum += node.val

            if node.left is not None:
                queue.append(node.left)

            if node.right is not None:
                queue.append(node.right)

        return range_sum