腾讯音乐9.8笔试

 def getBinaryTrees(self , preOrder: List[int], inOrder: List[int]) -> List[TreeNode]:
        # write code here
        ret = []
        def buildTree(preorder,inorder):
            if len(preorder)==0: return [None]
            x = preorder.pop(0)
            tree_list = []
            for i,val in enumerate(inorder):
                if val==x:
                    l_trees = buildTree(preorder[:i],inorder[:i])
                    r_trees = buildTree(preorder[i:],inorder[i+1:])
                    for l in l_trees:
                        for r in r_trees:
                            root = TreeNode(x)
                            root.left,root.right = l,r
                            tree_list.append(root)
            return tree_list
        
        ret = buildTree(preOrder,inOrder)
        return ret

def getTreeSum(self , tree: TreeNode) -> int:
        # write code here
        MOD = 10**9+7
        def dfs(node):
            if not node: return 0
            left = dfs(node.left)
            right = dfs(node.right)
            total = 1
            if left==right:
                total = (total+left+right)%MOD
            elif left>right:
                total = (total+left*2)%MOD
            else:
                total = (total+right*2)%MOD
            return total%MOD
        res = dfs(tree)
        return res