先序还原中序

def solve(____):
    preorder = list(map(int, preorder.split(____)))
    def get_inorder(____):
        if not pre:
            return []
        root = pre[____]
        left = [x for x in pre[____:] if x < root]
        right = [x for x in pre[____:] if x > root]
        return get_inorder(____) + [root] + get_inorder(____)
    result = get_inorder(____)
    print('____'.join(map(____)))