On the first day, I really felt like crying. It felt really uncomfortable to drag down my teammates (serious face). I didn't discuss it with them all day. They were not in good condition either. In the afternoon, I could only hear them frowning and saying nothing. In the silence, they said an unforgettable sentence: "It seems that our model has to be rebuilt." To be honest, this was the first time I felt what powerlessness and unwillingness meant, so I asked them for the MATLAB courseware and planned to study on my own. (Many students were surprised that I, the programmer in the team, had not started learning MATLAB at the end of the first day.) This is the fact. The progress on the first day can be said to be 0. I went back to my dormitory in the evening, took a shower (my teammates later told me that you still have time to take a shower hhhh), and started learning MATLAB. I have to say that although MATLAB has many functions, only few of them can be used in US competitions. I spent two hours to initially understand the basic operations of matlab, and then spent a few hours trying some small programs related to the competition questions. It was already two o'clock in the morning, so I immediately turned off the lights and went to bed. I rushed to their dormitory building early the next morning and showed them the results of my night. I am very grateful to my teammate 1. Not only did he not disappoint me, he became my best friend. He quickly locked onto the code for my cellular automaton and made the cellular automaton model the core of our thesis. Through this model, we used animations to vividly interpret the entire process of the spread of the virus. The infection status was highly consistent with the actual situation, allowing us to sweep away the previous decadence and get on the right track in the competition.