solution.py

# 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

"""
91 / 91 test cases passed.
Runtime: 68 ms
Memory Usage: 19.4 MB
"""
class Solution:
    def deleteNode(self, root: Optional[TreeNode], key: int) -> Optional[TreeNode]:
        if not root: return None
        if key > root.val: root.right = self.deleteNode(root.right, key)
        elif key < root.val: root.left = self.deleteNode(root.left, key)
        else:
            if not root.left: return root.right
            if not root.right: return root.left
            node = root.right
            while node.left:
                node = node.left
            node.left = root.left
            root = root.right
        return root