用筛法求之N内的素数

解题思路:

注意事项:

参考代码:

import java.util.Scanner;

public class Main {

public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNext()) {

            int a = scanner.nextInt();

            /*两个循环，外循环是放进来的数，内循环是把小于传进来的数的所有数进行取余判断一遍*/

            for(int i=2;i<=a;i++){

                for(int j=2;j<=i;j++){

                    //先把2除外

                    if(i==2){

                        System.out.println(i);

                        break;

                    }

                    //有除数并且除数不等于本身的数除外

                    if(i%j==0&&j!=i){

                        break;

                    }

                    //除了1和自身的除数，就是素数，输出。

                    else if(j==i){

                        System.out.println(i);

                    }

                }

            }

        }

    }

}