# 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 countNodes(self, root: TreeNode) -> int:
if not root:
return 0
return self.countNodes(root.left) + self.countNodes(root.right) + 11047. Remove All Adjacent Duplicates In String | 977. Squares of a Sorted Array |
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1748. Sum of Unique Elements | 897. Increasing Order Search Tree |
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700. Search in a Binary Search Tree | 590. N-ary Tree Postorder Traversal |
589. N-ary Tree Preorder Traversal | 1299. Replace Elements with Greatest Element on Right Side |
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