Question

How to find the prime numbers between 1 to 100 in Java

Answer 1

public class MyClass {
    public static void main(String args[]) {
        int count = 0;
        
        for (int n = 2; n <= 100; n++) {
            count = 0;
            for (int i = 2; i <= n / 2; i++) {
  	            if (n % i == 0) {
     	            count++;
  	                break;
	            }
            }
            if (count == 0) {
	            System.out.print(n + " ");
            } 
        }
    }
}




/*
run:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 

*/

 

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Answer 2

public class MyClass {
    static boolean isPrime(int n) {
        if (n < 2 || (n % 2 == 0 && n != 2)) {
            return false;
        }
         
        int count = (int)Math.floor(Math.sqrt(n));
        for (int i = 3; i <= count; i += 2) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }
    public static void main(String args[]) {
        for (int n = 2; n <= 100; n++) {
            if (isPrime(n)) {
                System.out.print(n + " ");
            } 
        }
    }
}
 
 
 
 
/*
run:
 
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 
 
*/

 

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