mergesort.java

import java.util.Scanner;

public class MergeSortScanner {

    public static void mergeSort(int[] arr) {
        if (arr.length <= 1) {
            return;
        }

        // Divide the array into two halves
        int mid = arr.length / 2;
        int[] left = new int[mid];
        int[] right = new int[arr.length - mid];
        System.arraycopy(arr, 0, left, 0, mid);
        System.arraycopy(arr, mid, right, 0, arr.length - mid);

        // Sort the two halves recursively
        mergeSort(left);
        mergeSort(right);

        // Merge the two sorted halves
        merge(arr, left, right);
    }

    private static void merge(int[] arr, int[] left, int[] right) {
        int i = 0;
        int j = 0;
        int k = 0;

        while (i < left.length && j < right.length) {
            if (left[i] <= right[j]) {
                arr[k] = left[i];
                i++;
            } else {
                arr[k] = right[j];
                j++;
            }
            k++;
        }

        // Copy the remaining elements of left, if there are any
        while (i < left.length) {
            arr[k] = left[i];
            i++;
            k++;
        }

        // Copy the remaining elements of right, if there are any
        while (j < right.length) {
            arr[k] = right[j];
            j++;
            k++;
        }
    }

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

        System.out.println("Enter the size of the array:");
        int n = scanner.nextInt();

        int[] arr = new int[n];

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

        mergeSort(arr);

        System.out.println("Sorted array:");
        for (int i = 0; i < n; i++) {
            System.out.print(arr[i] + " ");
        }

        scanner.close();
    }
}