Merge sort

//Merge sort

import java.util.*;

class Merge_Sort {
	static void printArray(int arr[]) {
        StringBuffer sb=new StringBuffer("");
        int n = arr.length;

        for(int i = 0; i < n; ++i)
            sb.append(arr[i] + " ");

        System.out.println(sb.toString());
    }

	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int T = sc.nextInt();

		while(T > 0) {
			int n = sc.nextInt();
			Merge_Sort ms = new Merge_Sort();
			int arr[] = new int[n];

			for(int i = 0; i < n; i++)
				arr[i] = sc.nextInt();

			Solution g = new Solution();
			g.mergeSort(arr, 0, arr.length - 1);
			ms.printArray(arr);
		  T--;
		}
	}
}

class Solution {
    void merge(int arr[], int l, int m, int r) {
        ArrayList<Integer> temp = new ArrayList<>();
        int left = l;
        int right = m + 1;
        
        while(left <= m && right <= r) {
            if(arr[left] <= arr[right]) {
                temp.add(arr[left]);
                left++;
            }
            else {
                temp.add(arr[right]);
                right++;
            }
        }
        
        while(left <= m) {
            temp.add(arr[left]);
            left++;
        }
        
        while(right <= r) {
            temp.add(arr[right]);
            right++;
        }
        
        for(int i = l; i <= r; i++) {
            arr[i] = temp.get(i - l);
        }
    }
    
    void mergeSort(int arr[], int l, int r) {
        if(l >= r) {
            return;
        }
        
        int mid = (l + r) / 2;
        mergeSort(arr, l, mid);
        mergeSort(arr, mid + 1, r);
        merge(arr, l, mid, r);
    }
}