assignment for the programing class in USTC by zyj.

The experiment was done on ubuntu 16.04. I used python3.6 in the environment of Anaconda.

3b and 4b obtain figures for the experiment of 3body and 4 body respetctively. When you want to see the line chart in the report or redo the experiment yourself, first you should have installed tensorflow and tensorboardX, the tutorial can tell you how to function: https://www.jianshu.com/p/46eb3004beca (the file name shall be "3b" or "4b" but not "runs" if you want to see my figures)