Hi, can anyone describe this Code with the following question.. New version Just

Question

Hi, can anyone describe this Code with the following question.. New version Just Describe in python. An algorithm that sorts key-value entries by key is said to be straggling if, any time two entries ei and ej have equal keys, but ei appears before ej in the input, then the algorithm places ei after ej in the output. Describe a change to the merge-sort algorithm in Section 12.2 to make it straggling.

#section 12.2

def merge_sort(S):

n = len(S)

if n < 2:

return

  mid = n // 2

S1 = S[0:mid]

S2 = S[mid: n]

merge _sort(S1)

merge _sort(S2)

merge results 14 merge (S1, S2, S)

Explanation / Answer

# Python program for implementation of MergeSort

# Merges two subarrays of arr[].

# First subarray is arr[l..m]

# Second subarray is arr[m+1..r]

def merge(arr, l, m, r):

n1 = m - l + 1

n2 = r- m

# create temp arrays

L = [0] * (n1)

R = [0] * (n2)

# Copy data to temp arrays L[] and R[]

for i in range(0 , n1):

L[i] = arr[l + i]

for j in range(0 , n2):

R[j] = arr[m + 1 + j]

# Merge the temp arrays back into arr[l..r]

i = 0 # Initial index of first subarray

j = 0 # Initial index of second subarray

k = l # Initial index of merged subarray

while i < n1 and j < n2 :

# The belo line change the ordering of the element in input sequence to output Sequence

if L[i] <R[j]:

arr[k] = L[i]

i += 1

else:

arr[k] = R[j]

j += 1

k += 1

# Copy the remaining elements of L[], if there

# are any

while i < n1:

arr[k] = L[i]

i += 1

k += 1

# Copy the remaining elements of R[], if there

# are any

while j < n2:

arr[k] = R[j]

j += 1

k += 1

# l is for left index and r is right index of the

# sub-array of arr to be sorted

def mergeSort(arr,l,r):

if l < r:

# Same as (l+r)/2, but avoids overflow for

# large l and h

m = (l+(r-1))/2

# Sort first and second halves

mergeSort(arr, l, m)

mergeSort(arr, m+1, r)

merge(arr, l, m, r)

# Driver code to test above

arr = [12, 11, 13, 5, 6, 7]

n = len(arr)

print ("Given array is")

for i in range(n):

print ("%d" %arr[i]),

mergeSort(arr,0,n-1)

print (" Sorted array is")

for i in range(n):

print ("%d" %arr[i]),

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