Delete Leaves With a Given Value — Python

# Time:  O(n)
# Space: O(h)

# Definition for a binary tree node.
class TreeNode(object):
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None


class Solution(object):
    def removeLeafNodes(self, root, target):
        """
        :type root: TreeNode
        :type target: int
        :rtype: TreeNode
        """
        if not root:
            return None
        root.left = self.removeLeafNodes(root.left, target)
        root.right = self.removeLeafNodes(root.right, target)
        return None if root.left == root.right and root.val == target else root