Java bootcamp · Lab 25

Is prime?

mediumFor12 minLesson: For Loop

Read the question, write Java on the right, then Run or Check.

QuestionHint and solution stay closed until you open them

Read n ≥ 2; print yes if prime else no.

Examples

Example 1
Input
7
Output
yes
Example 2
Input
9
Output
no
Hint
  1. Trial division up to sqrt(n).
Show correct code

Peek only after you have tried. You can still Check your own version.

import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int n = in.nextInt();
    boolean ok = n >= 2;
    for (int d = 2; d * (long) d <= n; d++) if (n % d == 0) { ok = false; break; }
    System.out.println(ok ? "yes" : "no");
  }
}
Main.javaJava 21 · javac · Ctrl + Enter runs
ResultIdle
Run to see output. Check grades the tests.