题解 | #修剪叶子#

自顶向下，判断叶子节点的父节点，如果是将其删除，注意左右子节点有一个是叶子节点即可

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return TreeNode类
#
class Solution:
    
    def pruneLeaves(self , root ):
        # write code here
        def leaf(node):
            if not node: return False
            return not node.left and not node.right
        
        def check(node):
            if not node: return False
            if leaf(node.left) or leaf(node.right):
                return True
            return False
        def inOrder(root):
            if not root or check(root):
                return None
            root.left = inOrder(root.left)
            root.right = inOrder(root.right)
            return root
        root = inOrder(root)
        return root