使用Eratosthenes算法编写程序，求20000以内的素数，每隔500为一个测试点，每个测试点计算五次，记录每次的运行时间求平均值，结合计算机硬件配置以及运行时间随数据规模的增大的变化情况分析计算机性能。-To write programs using the Eratosthenes algorithm, find the prime numbers less than 20,000, every 500 to a test point, the calculation for each test point five times, recording each of the running time of an average, a combination of computer hardware configuration and run-time increases with the size of the data analysis of major changes in computer performance.