Question

Using Python, remove the slice operator from the mergeSort function. The new code will look a lot like the provided code except that you will be merging from the list being sorted into a temporary list. So take some time to understand exactly what the code in the book is doing before using it as a template for what you will need to add to the new function.

def mergeSort(alist, workspace=None, start=None, end=None):

#### You can change this code if you want to, but it sufficient to implement a solution.

if workspace is None:
workspace = [None] * len(alist)
start = 0
end = len(alist) #### Note that end is not a valid index into the array -- it's one past the last element!

if end-start <= 1:
return

midpoint = (start+end)//2

mergeSort(alist, workspace, start, midpoint)
mergeSort(alist, workspace, midpoint, end)

Answer 1

//Python program

def merge(alist, workspace,l, m, r):
temp_pos=l
size=r-l+1
left_end=m-1
while l<=left_end and m<=r:
if alist[l]<alist[m]:
workspace[temp_pos]=alist[l]
l=l+1
else:
workspace[temp_pos]=alist[m]
m=m+1
temp_pos=temp_pos+1
while l<=left_end:
   workspace[temp_pos]=alist[l]
   l=l+1
   temp_pos = temp_pos+1
  
   while m<=r:
   workspace[temp_pos]=alist[m]
   m=m+1
   temp_pos = temp_pos+1
   i=0
  
   while i<size:
       alist[r]=workspace[r];
       r=r-1
       i=i+1
  
def mergeSort(alist,workspace,start,end):
if l < r:
mid = start+(end-l)/2
  
# Sort first and second halves
mergeSort(alist, workspace,start,mid)
mergeSort(alist, workspace,mid+1, end)
merge(alist, workspace,start, mid+1, end)