Java Program to Maximize difference between sum of prime and non-prime array elements by left shifting of digits minimum number of times

// java program for the above approach
import java.io.*;
import java.lang.*;
import java.util.*;

class GFG {

    // Function to check if a
    // number is prime or not
    static boolean isPrime(int n)
    {

        // Base cases
        if (n <= 1)
            return false;
        if (n <= 3)
            return true;

        // Check if the number is
        // a multiple of 2 or 3
        if (n % 2 == 0 || n % 3 == 0)
            return false;

        int i = 5;

        // Iterate until square root of n
        while (i * i <= n) {

            // If n is divisible by both i and i + 2
            if (n % i == 0 || n % (i + 2) == 0)
                return false;
            i = i + 6;
        }
        return true;
    }

    // Function to left shift a number
    // to maximize its contribution
    static int[] rotateElement(int n)
    {

        // Convert the number to string
        String strN = Integer.toString(n);

        // Stores the maximum prime number
        // that can be obtained from n
        int maxPrime = -1;

        // Store the required
        // number of operations
        int cost = 0;

        String temp = strN;

        // Check for all the left
        // rotations of the number
        for (int i = 0; i < strN.length(); i++) {

            // If the number is prime, then
            // take the maximum among them
            if (isPrime(Integer.parseInt(temp))
                && Integer.parseInt(temp) > maxPrime) {
                maxPrime = Integer.parseInt(temp);
                cost = i;
            }

            // Left rotation
            temp = temp.substring(1) + temp.charAt(0);
        }

        int optEle = maxPrime;

        // If no prime number can be obtained
        if (optEle == -1) {
            optEle = Integer.MAX_VALUE;
            temp = strN;

            // Check all the left
            // rotations of the number
            for (int i = 0; i < strN.length(); i++) {

                // Take the minimum element
                if (Integer.parseInt(temp) < optEle) {
                    optEle = Integer.parseInt(temp);
                    cost = i;
                }

                // Left rotation
                temp = temp.substring(1) + temp.charAt(0);
            }
            optEle *= (-1);
        }
        return new int[] { optEle, cost };
    }

    // Function to find the maximum sum
    // obtained using the given operations
    static void getMaxSum(int arr[])
    {

        // Store the maximum sum and
        // the number of operations
        int maxSum = 0, cost = 0;

        // Traverse array elements
        for (int x : arr) {

            // Get the optimal element and the
            // number of operations to obtain it
            int ret[] = rotateElement(x);

            int optEle = ret[0], optCost = ret[1];

            // Increment the maximum difference
            // and number of operations required
            maxSum += optEle;
            cost += optCost;
        }

        // Print the result
        System.out.println("Difference = " + maxSum + " , "
                           + "Count of operations = "
                           + cost);
    }

    // Driver Code
    public static void main(String[] args)
    {

        // Given array arr[]
        int arr[] = { 541, 763, 321, 716, 143 };

        // Function call
        getMaxSum(arr);
    }
}