Java Program to Find Greatest Prime and Smallest Composite with n root time complexity.

WHAT IS PRIME NUMBER ?

Prime numbers are whole numbers which can be divisible only by one and itself to get remainder of zero.

WHAT IS COMPOSITE NUMBER ?

Composite Numbers are whole numbers which can be divisible by more than two numbers to get the remainder of zero.

PROGRAM

A Java program to find Greatest Prime and Smallest Composite from n number of Inputs.

import java.util.*; public class Solution{ public static void main(String[] args) { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); int a[] = new int[n]; System.out.println("Enter the numbers: \n"); for(int i=0; i<n; i++) { a[i] = sc.nextInt(); } int greatprime = Integer.MIN_VALUE; int smallcomposite = Integer.MAX_VALUE; for(int j=0; j<n; j++){ boolean prime = true; boolean composite = false; if(a[j] != 1){ for(int i=2; i*i <= a[j]; i++){ if(a[j] % i == 0 ) { prime = false; composite = true; break; } } }else prime = false; if(a[j] == 2) composite = false; if(prime && a[j] > greatprime) greatprime = a[j]; if(composite && a[j] < smallcomposite) smallcomposite = a[j]; } if(greatprime < 1) { System.out.println("There is no prime number"); } else System.out.println("Greatest Prime number is: "+greatprime); if(smallcomposite == Integer.MAX_VALUE) { System.out.println("There is no composite number"); } else System.out.println("Smallest Composite number is: "+smallcomposite); } }

OUTPUT

10 Enter the numbers: 5 2 7 11 13 17 19 101 5 37 Greatest Prime number is: 101 There is no composite number