圆周率Pi的经典算法，利用常用的线性统计概率算法。-Pi pi classic algorithm, the use of commonly used linear statistical probability algorithm.

使用概率算法和定积分知识来计算圆周率，可以参考，是算法设计的人们程序-The use of probabilistic algorithms and knowledge of the definite integral to calculate circumference rate, to refer to people who are algorithm design process