dsa/Basic/CheckPrime.java

// write a code in java to check for prime numbers in o(n^1/2) time complexity using function

import java.util.Scanner;

class CheckPrime {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a number to check if it is prime or not: ");
        int num = scanner.nextInt();
        scanner.close();
        if (isPrime(num)) {
            System.out.println(num + " is a prime number");
        } else {
            System.out.println(num + " is not a prime number");
        }
    }

    static boolean isPrime(int num) {
        if (num <= 1) {
            return false;
        }
        for (int i = 2; i * i <= num; i++) {
            if (num % i == 0) {
                return false;
            }
        }
        return true;
    }
}