MergeSort

import java.util.Scanner;

public class MergeSort {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the number of elements in the array: ");
        int n = scanner.nextInt();
        int[] array = new int[n];

        System.out.println("Enter the elements of the array:");
        for (int i = 0; i < n; i++) {
            array[i] = scanner.nextInt();
        }

        System.out.println("Unsorted Array:");
        printArray(array);

        mergeSort(array, 0, array.length - 1);

        System.out.println("\nSorted Array:");
        printArray(array);

        scanner.close();
    }

    public static void mergeSort(int[] array, int left, int right) {
        if (left < right) {
            int mid = (left + right) / 2;

            // Sort first and second halves
            mergeSort(array, left, mid);
            mergeSort(array, mid + 1, right);

            // Merge the sorted halves
            merge(array, left, mid, right);
        }
    }

    public static void merge(int[] array, int left, int mid, int right) {
        int n1 = mid - left + 1;
        int n2 = right - mid;

        // Temporary arrays
        int[] leftArray = new int[n1];
        int[] rightArray = new int[n2];

        // Copy data to temporary arrays
        System.arraycopy(array, left, leftArray, 0, n1);
        System.arraycopy(array, mid + 1, rightArray, 0, n2);

        int i = 0, j = 0;
        int k = left;

        // Merge the temporary arrays back into array
        while (i < n1 && j < n2) {
            if (leftArray[i] <= rightArray[j]) {
                array[k] = leftArray[i];
                i++;
            } else {
                array[k] = rightArray[j];
                j++;
            }
            k++;
        }

        // Copy remaining elements of leftArray
        while (i < n1) {
            array[k] = leftArray[i];
            i++;
            k++;
        }

        // Copy remaining elements of rightArray
        while (j < n2) {
            array[k] = rightArray[j];
            j++;
            k++;
        }
    }

    public static void printArray(int[] array) {
        for (int num : array) {
            System.out.print(num + " ");
        }
        System.out.println();
    }
}