用计算机模拟一个随机事件，蒲丰投针的实验，并估计随机事件发生的概率以计算圆周率pi，并分析所设计的随机实验中各因素的影响。(A computer simulation of random events, such as Buffon needle experiment, and estimate the probability of random events to compute PI, and analyze the influencing factors in the design of random experiment.)