// write a code of mergesort using function in java

import java.util.ArrayList;
import java.util.Scanner;
public class MergeSort{
    // use notation beginning, mid and end

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the size of the array: ");
        int n = sc.nextInt();
        int[] arr = new int[n];
        System.out.println("Enter the elements of the array: ");
        for(int i=0; i<n; i++){
            arr[i] = sc.nextInt();
        }
        mergeSort(arr, 0, n-1);
        System.out.println("The sorted array is: ");
        for(int i=0; i<n; i++){
            System.out.print(arr[i] + " ");
        }
        sc.close();
    }

    static void mergeSort(int arr[], int beginning, int end){
        if(beginning < end){
            // find the middle point
            int mid = (beginning + end) / 2;
    
            // sort first and second halves
            mergeSort(arr, beginning, mid);
            mergeSort(arr, mid + 1, end);
    
            // merge the sorted halves
            merge(arr, beginning, mid, end);
        }
    }
  
    static void merge(int[] arr, int low, int mid, int high) {
        ArrayList<Integer> temp = new ArrayList<>(); // temporary array
        int left = low;      // starting index of left half of arr
        int right = mid + 1;   // starting index of right half of arr

        //storing elements in the temporary array in a sorted manner//

        while (left <= mid && right <= high) {
            if (arr[left] <= arr[right]) {
                temp.add(arr[left]);
                left++;
            } else {
                temp.add(arr[right]);
                right++;
            }
        }

        // if elements on the left half are still left //

        while (left <= mid) {
            temp.add(arr[left]);
            left++;
        }

        //  if elements on the right half are still left //
        while (right <= high) {
            temp.add(arr[right]);
            right++;
        }

        // transfering all elements from temporary to arr //
        for (int i = low; i <= high; i++) {
            arr[i] = temp.get(i - low);
        }
    }
    
}