The updated version differs from the original version primarily in the following aspects:

1. The textual expression of the Introduction section has been reorganized.

2. The textual expression of the Related Work section has been reorganized.

3. The textual expression of the Method section has been reorganized. For better understanding, we have switched to describing our method in a discrete scenario, along with some modifications to notations. It's important to note that the method itself has not changed; we are only discussing it in the context of discrete scenarios instead of continuous ones for better illustration.

4. In response to the reviewer's comments, a new section 5.5 has been added to discuss the selection of the proxy model.

5. In response to the reviewer's comments, Table 8 discussing the cost has been added to the appendix.

6. In response to the reviewer's comments, Table 9 providing information on the training data for each stage has been added to the appendix.

7. In response to the reviewer's comments, a discussion about the order of n has been added to the appendix, presented in Table 14.