mergeSort.py

def mergeSort(alist):
    if len(alist) == 1:
        return alist
    
    if len(alist) > 1:
        mid = len(alist)//2
        leftList = alist[:mid]
        rightList = alist[mid:]
        
        mergeLeft = mergeSort(leftList)
        mergeRight = mergeSort(rightList)
    
        resultMerge = popmin(mergeLeft,mergeRight)

        return resultMerge

def popmin(left,right):
    result = []
    while left or right:

        if not left:
            result.append(right[0])
            right.pop(0)

        elif not right:
            result.append(left[0])
            left.pop(0)

        elif left[0] >= right[0]:
            result.append(right[0])
            right.pop(0)

        elif right[0] >= left[0]:
            result.append(left[0])
            left.pop(0)

    return result

listNumber = [6,5,3,1,8,7,2,4]
print (mergeSort(listNumber))