JAVA 基础编程练习题44 【程序 44 偶数的素数和】

44 【程序 44 偶数的素数和】

题目：一个偶数总能表示为两个素数之和。

package cskaoyan;

public class cskaoyan44 {
@org.junit.Test
public void sum() {
java.util.Scanner in = new java.util.Scanner(System.in);
long number = 0;

do {
System.out.println("请输入一个偶数:");
number = in.nextLong();
} while (number % 2 != 0);

for (long i = 2; i < number; i++) {
if (isPrime(i) && isPrime(number - i)) {
System.out.println("偶数" + number + "可以分解成" + i + "和" + (number - i) + "两个素数的和");
break;
}
}

in.close();
}

private static boolean isPrime(long number) {
boolean flag = true;

if (number < 2) {
flag = false;
} else if (number < 4) {
flag = true;
} else if (number % 2 == 0) {
flag = false;
} else {
for (long i = 3; i < Math.sqrt(number) + 1; i++) {
if (number % i == 0) {
flag = false;
break;
}
}
}

return flag;
}
}

转载于:https://www.cnblogs.com/denggelin/p/11490192.html