Identify Prime Numbers
Question
Write an algorithm to identify prime numbers from a list of numbers ranging 0100.
Solution
The main question is actually to write a program to check if a number is prime. There are 4 situations.

If number is 0 or 1, it is not prime.

if the number is 2, it is prime.

if the number is even, it is not prime.

if number is greater than 3, and not divisible by all odd numbers (except 1) smaller than the square root of the input number, it is prime.
Sample
public class InterviewPracticeExtra05 {
private static boolean is_prime(int input) {
if (input <= 1) return false;
if (input == 2) return true;
if (input % 2 == 0) return false;
for (int i = 3; i * i <= input; i += 2) {
if (input % i == 0) return false;
}
return true;
}
public static void main(String[] args) {
for (int i = 0; i <= 100; i++) {
if (is_prime(i)) System.out.println(i);
}
}
}
Reference
Nicholas Workshop Newsletter
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