Count percentile

percentile.py

class Node:
    def __init__(self, n: int):
        self.val = n
        self.left = self.right = None

def percentageUnderNum(root: Node, threshold: int, depth: int) -> float:
    def helper(node: Node, count: int, total: int, curDepth: int) -> [int]:
        output = [count, total]
        if not node or curDepth > depth:
            return output
        if node.val < threshold:
            output[0] += 1
        left = helper(node.left, count, total + 1, curDepth + 1)
        right = helper(node.right, count, total + 1, curDepth + 1)
        return [left[0] + right[0], left[1] + right[1]]
    rootOutput = helper(root, 0, 0, 0)
    return rootOutput[0] / rootOutput[1]