Results 4 issues of Hao Sun

Added IPCO 2020 and 2021 APPROX graph theory and probablistic methods and Parameterized algorithms lectures

LLNCS conflicts with thmtools, in particular with thm-restate. This causes an error where prop is both undefined and when you try to define it it tells you it's already defined....

compatibility
llncs

You can see here that ![Image](https://github.com/user-attachments/assets/50dfa4c6-5fb3-4ec9-96ba-c436f4be512f) the arrow is not at the midpoint of the curve. Midpointed is selected under reverse arrow shape.

### Description of the bug AttributeError: 'Rect' object has no attribute 'get_area' [ltow.py](https://github.com/user-attachments/files/23146939/ltow.py) [FVShard.pdf](https://github.com/user-attachments/files/23146938/FVShard.pdf) ### How to reproduce the bug Run the following code C:\Users\hao_s\Downloads>py ltow.py [INFO] Start to convert...