"Diduo Enclosure" Tian Ji racer Cao Chong said that there was a story about the construction of Ding Wei in Song Dynasty in ancient China, which also included the idea of operational research. Legend has it that when Song Zhenzong was in power, the palace caught fire. Overnight, a large area of palaces, terraces, halls and pavilions became ruins. In order to restore these palaces, Song Zhenzong put Ding Wei, the Duke of Jin at that time, in charge of the restoration project. At that time, to complete this major construction project, there were three major problems: first, a large number of ruins and garbage needed to be removed; Second, it needs to transport a lot of wood and stones; Third, we need to transport a lot of new soil. Whether it is transporting garbage or transporting building materials and new soil, it involves a lot of transportation problems. If the arrangement is improper, the construction site will be chaotic, and the normal traffic and life order will be seriously affected. Ding Wei Song Dynasty, after studying the project, formulated such a construction scheme: firstly, several large deep ditches were dug from the construction site, and the excavated soil was used as new soil for construction, thus solving the problem of new soil. The second step is to introduce Bianshui from outside the city into the dug ditch, so that the wood and stone can be transported by rafts and ships, thus solving the transportation problem of wood and stone. Finally, after the material transportation task is completed, the water in the ditch is drained, and the garbage on the construction site is filled into the ditch, so that the ditch is leveled again. A simple summary is such a process: digging ditches (taking soil) → diverting water into ditches (transporting by water) → filling ditches (treating garbage). According to this construction scheme, it not only saves a lot of time and money, but also makes the construction site orderly, so that the traffic and life order of the city are not greatly affected by the construction. It is indeed a very scientific construction scheme.