Merge sort

#User function Template for python3
https://practice.geeksforgeeks.org/problems/merge-sort/1
class Solution:
    def mergeSort(self,arr, l, r):
        def use(arr):
            if len(arr)<=1:
                return
            mid=len(arr)//2
            L=arr[:mid]
            R=arr[mid:]
            use(L)
            use(R)
            m,n=len(L),len(R)
            i=j=k=0
            while i<m and j<n:
                if L[i]<R[j]:
                    arr[k]=L[i]
                    i=i+1
                else:
                    arr[k]=R[j]
                    j=j+1
                k=k+1
            while i<m:
                arr[k]=L[i]
                i=i+1
                k=k+1
            while j<n:
                arr[k]=R[j]
                j=j+1
                k=k+1
            return arr
        return use(arr)


#{
#  Driver Code Starts
#Initial Template for Python 3



if __name__ == "__main__":
    t=int(input())
    for i in range(t):
        n=int(input())
        arr=list(map(int,input().split()))
        Solution().mergeSort(arr, 0, n-1)
        for i in range(n):
            print(arr[i],end=" ")
        print()
# } Driver Code Ends