您所在位置：主题：初学，书上的一道结构化程序设计算法例题，没看懂，请指教，谢谢！
lnddshw
[专家分：0] 发布于 2008-06-17 17:36:00
请指教！书上的一道结构化程序设计算法例题，没看懂，谢谢！
题：
采用“（Eratosthenes）筛法”来求素数。将1到1000之间的素数打印出来。
_________________________________________
| |输入n |
|________________________________________
| 1=>I |
|________________________________________
| 当i≤n |
| _______________________________
| | i=>X I |
¬| |_______________________________
| | i+1=>I |
|_________|_______________________________
| 0=>X i |
|________________________________________
| 2=>I |
|________________________________________
| 当i＜√n(取整部分) |
| __________________________________|
| | \ Xi=0/ | 请问 Xi=0的数是哪些？
| | \ / |
| |是_\_/_否__________________________|
| | | i+1=>j |
| | |______________________________|
| | | 当j≤0 |
| | | __________________________|
| | | | \ X j=0/ | 请问X j=0的数是哪些？
| | | |是 \ /否 |
| | | |____\/_____________________|
| | | | | \ Xj能被Xi整除/ |
| | | | | \ / |
| | | | |是 \ / 否 |
| | | | |______\____/_________|
| | | | |0=> Xj| | |
| | |____|_____|______ |_____________|
| | | j+1=>j |
| | |_____________________________|
| | | i+1=>i |
|______|____ |______________________________|
| 1=>i |
|_________________________________________|
| 当i≤n |
| ___________________________________|
| | \ Xi=0 / |
| |_____是_____\____/________否_______|
| | | 输出Xi |
| |________________ |_________________|
| | i+1=>i |
|______|__________________________________|
题：
采用“（Eratosthenes）筛法”来求素数。将1到1000之间的素数打印出来。
_________________________________________
| |输入n |
|________________________________________
| 1=>I |
|________________________________________
| 当i≤n |
| _______________________________
| | i=>X I |
¬| |_______________________________
| | i+1=>I |
|_________|_______________________________
| 0=>X i |
|________________________________________
| 2=>I |
|________________________________________
| 当i＜√n(取整部分) |
| __________________________________|
| | \ Xi=0/ | 请问 Xi=0的数是哪些？
| | \ / |
| |是_\_/_否__________________________|
| | | i+1=>j |
| | |______________________________|
| | | 当j≤0 |
| | | __________________________|
| | | | \ X j=0/ | 请问X j=0的数是哪些？
| | | |是 \ /否 |
| | | |____\/_____________________|
| | | | | \ Xj能被Xi整除/ |
| | | | | \ / |
| | | | |是 \ / 否 |
| | | | |______\____/_________|
| | | | |0=> Xj| | |
| | |____|_____|______ |_____________|
| | | j+1=>j |
| | |_____________________________|
| | | i+1=>i |
|______|____ |______________________________|
| 1=>i |
|_________________________________________|
| 当i≤n |
| ___________________________________|
| | \ Xi=0 / |
| |_____是_____\____/________否_______|
| | | 输出Xi |
| |________________ |_________________|
| | i+1=>i |
|______|__________________________________|