Merge Sort

Given an array of integers, sort the elements in the array in ascending order. The merge sort algorithm should be used to solve this problem.

Examples:

{1} is sorted to {1}
{1, 2, 3} is sorted to {1, 2, 3}
{3, 2, 1} is sorted to {1, 2, 3}
{4, 2, -3, 6, 1} is sorted to {-3, 1, 2, 4, 6}

class Solution(object):
  def mergeSort(self, array):
    if len(array) <= 1:
      return array
    mid = len(array)/2
    left = self.mergeSort(array[:mid])
    right = self.mergeSort(array[mid:])
    return self.merge(left,right)
  
  
  def merge(self,left,right):
    l,r = 0,0
    res = []
    while l < len(left) and r < len(right):
      if left[l] < right[r]:
        res.append(left[l])
        l += 1
      else:
        res.append(right[r])  
        r += 1
    res += left[l:]
    res += right[r:]
    return res