二叉树的中序序列和后序序列来求前序序列的代码，用堆栈来实现。

以下是二叉树的中序序列和后序序列来求前序序列的代码，用堆栈来实现：

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def buildTree(inorder, postorder):
    if not inorder or not postorder:
        return None
    root = TreeNode(postorder[-1])
    stack = [root]
    i, j = len(inorder)-1, len(postorder)-2
    while j >= 0:
        node = TreeNode(postorder[j])
        parent = None
        while stack and stack[-1].val == inorder[i]:
            parent = stack.pop()
            i -= 1
        if parent:
            parent.left = node
        else:
            stack[-1].right = node
        stack.append(node)
        j -= 1
    return root

def preorderTraversal(root):
    if not root:
        return []
    stack, res = [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

其中，`buildTree`函数用于构建二叉树，`preorderTraversal`函数用于求出前序序列。