求素数

（一）求100以内的素数

<span style="font-size:14px;">class Noname1{public static void main(String []args){for (int i = 200; i <= 1000; i++) {int temp = (int) Math.sqrt(i);// 我把那个aqrt单独提出来,这样速度稍微快一点,虽然在100内变化不大,但如果是10000000内的素数呢?if (i <= 3) {System.out.println(i + " is a prime");} else {for (int j = 2; j <= temp; j++) {// 把Math.sqrt(i)转换为int类形if (i % j == 0) {break;}if (j >= temp) {System.out.println(i + " is a prime");}}}}}}</span>

（二）求n到m之间的素数

<span style="font-size:18px;">class Noname1{public static void main(String []args){int n=2,m=100;for (int i = n; i < m; i++) {int temp = (int)Math.sqrt(i);if(i<=3){System.out.println(i+" is a prime");}for (int j = 2; j <= temp; j++) {if(i%j==0){break;}if(j>=temp){System.out.println(i+" is a prime");}}}}}</span>