Easy

Maximum Depth of Binary Tree

017

Given a binary tree encoded as level-order with -100000 as null, return its maximum depth.

EXAMPLES

Example 1

Input
{
  "root": [
    3,
    9,
    20,
    -100000,
    -100000,
    15,
    7
  ]
}

Output
3

FUNCTION SHAPE

root: intArray→int

SOLUTION NOTE

Postorder. The max depth at a node is the max of left and right depths + 1 for the current node.

Reveal reference solution +

pythonREFERENCE

def maxDepth(self, root: TreeNode) -> int:
    if not root:
        return 0
    return 1 + max(self.maxDepth(root.left),
                   self.maxDepth(root.right))

TimeO(n)

SpaceO(h)

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