1994: from Security Guard at Peking University to Professor at Tsinghua University

[No rebirth] + [No system] + [Grassroots struggle] + [Family grudges] + [Love and hatred of many women] + [Rise of scientific research] + [Business empire] In 1993, in order to save his seriously ill father, Zhang Shidan, a student of Yanshui Middle School with excellent academic performance, had to make a deal with his uncle Zhang Yuqing, who was the director of the commerce bureau in the county. His college entrance examination results were replaced by his cousin Zhang Shijie, and he himself lost his reputation. In order to support his family, Zhang Shidan went to Peking University to work as a security guard after comprehensive consideration. However, he never gave up his personal struggle. While working as a security guard, he applied for the self-study junior college in computer science at Peking University. He obtained the self-study junior college diploma in computer science in one and a half years. He was successfully admitted to the graduate school of Tsinghua University's computer science department and stayed at Tsinghua University to teach after graduation. In the process of personal struggle, he made many contributions in the computer field, and was successfully promoted to professor at Tsinghua University and became a well-known computer expert in China. He started his own business at the age of 30 and built his own IT empire.