说明：  一个求素数个数的程序 算pi(1000000000)不要1秒每个块如果10 0000, 需要 < 100000次全搜索加上8000 * 8000 < 6400 0000 总的次数小于7000 0000,就是说,搜索次数大大降低
(for a few number-counting procedures pi (1000000000) not a second of each block of 10 0000, the need lt; Search 100,000 plenary with 8,000* 8,000 lt; 6400 0000 total is less than the number 7000 0000, that is to say, greatly reducing the number of search)