Java Online Compiler
Example: Optimized Prime Number Check in Java
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Main.java
STDIN
Run
// Optimized Prime Number Check import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print("Enter a number: "); int number = scanner.nextInt(); boolean isPrime = true; if (number <= 1) { isPrime = false; } else { // Loop from 2 up to the square root of the number // We cast Math.sqrt(number) to int because loop counter is int for (int i = 2; i * i <= number; i++) { // Equivalent to i <= Math.sqrt(number) if (number % i == 0) { isPrime = false; break; } } } if (isPrime) { System.out.println(number + " is a prime number."); } else { System.out.println(number + " is not a prime number."); } scanner.close(); } }
Output
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