以下代码实现的是二叉树的中序遍历:
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
def traverse(root):
if root is None:
return
traverse(root.left)
print(root.val, end=" ")
traverse(root.right)