根据后序和中序遍历输出先序遍历用oython 解决

根据后序和中序遍历输出先序遍历的Python代码如下：

class TreeNode:
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

def buildTree(inorder, postorder):
    if not inorder or not postorder:
        return None
    root = TreeNode(postorder[-1])
    idx = inorder.index(root.val)
    root.left = buildTree(inorder[:idx], postorder[:idx])
    root.right = buildTree(inorder[idx+1:], postorder[idx:-1])
    return root

def preorderTraversal(root):
    if not root:
        return []
    res = []
    stack = [root]
    while stack:
        node = stack.pop()
        res.append(node.val)
        if node.right:
            stack.append(node.right)
        if node.left:
            stack.append(node.left)
    return res

inorder = [3, 7, 4, 18, 1, 5, 3, 11, 2, 6, 4]
postorder = [3, 4, 7, 1, 3, 5, 2, 4, 6, 11, 18]
root = buildTree(inorder, postorder)
preorder = preorderTraversal(root)
print(preorder)

其中，`buildTree`函数用于根据中序遍历和后序遍历构建二叉树，`preorderTraversal`函数用于输出先序遍历。你可以将中序遍历和后序遍历替换成你自己的数据，然后运行代码即可得到先序遍历的结果。