TheAlgorithms-Java/Maths/PrimeCheck.java at master · windNight/TheAlgorithms-Java · GitHub

38 lines (34 loc) · 827 Bytes

package Maths;

import java.util.Scanner;

public class PrimeCheck {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

System.out.print("Enter a number: ");

int n = scanner.nextInt();

if (isPrime(n)) {

System.out.println(n + " is a prime number");

} else {

System.out.println(n + " is not a prime number");

}

scanner.close();

}

/***

* Checks if a number is prime or not

* @param n the number

* @return {@code true} if {@code n} is prime

public static boolean isPrime(int n) {

if (n == 2) {

return true;

}

if (n < 2 || n % 2 == 0) {

return false;

}

for (int i = 3, limit = (int) Math.sqrt(n); i <= limit; i += 2) {

if (n % i == 0) {

return false;

}

return true;

}

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