merge sort

class :
    """
    @param A: an integer array
    @return: nothing
    """
    def sortIntegers2(self, A):
        
        self.mergesort(A)
    
    def mergesort(self,A):
        if len(A) > 1:
            mid = len(A) // 2
            L = A[0:mid]
            R = A[mid:len(A)]
            self.mergesort(L)
            self.mergesort(R)
            i = j = k = 0
            while i < len(L) and j < len(R):
                if L[i] < R[j]:
                    A[k] = L[i]
                    i+=1
                else:
                    A[k] = R[j]
                    j+=1
                k+=1
            while  i < len(L):
                A[k] = L[i]
                i+=1
                k+=1
            while j < len(R):
                A[k] = R[j]
                j+=1
                k+=1