A2513220233_ex2.zip.zip

import java.util.ArrayList; import java.util.List; public class A2513220238_ex2_p_1 { // 判断一个数是否是素数 public static boolean isPrime(int num) { if (num <= 1) { return false; } for (int i = 2; i <= Math.sqrt(num); i++) { if (num % i == 0) { return false; } } return true; } // 找到[2, N]范围内的所有素数 public static List<Integer> findPrimes(int N) { List<Integer> primes = new ArrayList<>(); for (int i = 2; i <= N; i++) { if (isPrime(i)) { primes.add(i); } } return primes; } public static void main(String[] args) { if (args.length != 1) { System.out.println("Usage: java PrimeNumbers N"); return; } int N = Integer.parseInt(args[0]); if (N < 2) { System.out.println("N must be greater than or equal to 2."); return; } List<Integer> primeNumbers = findPrimes(N); System.out.println("Prime numbers between 2 and " + N + ":"); for (int prime : primeNumbers) { System.out.print(prime + " "); } } }