Merge Sort: The Algorithm

This is it. The last time I wrote about Merge Sort was last night last week and now I will show you the fun.

So here’s the code I’ve written in 9 minutes 42 seconds (almost 10 minutes!) straight.

``````from random import randint

def sample_list(n, r):
result = []
for c in range(0, n):
result.append(randint(0, r))

return result

def merge(left, right):
i, j = 0, 0

result = []

while i < len(left) and j < len(right):
if left[i] <= right[j]:
result.append(left[i])
i += 1
else:
j += 1

if i < len(left):
result += left[i:]

if j < len(right):
result += right[j:]

return result

def sort(mylist):
if len(mylist) < 2:
return mylist

midlist = len(mylist) / 2
left_list = mylist[:midlist]
right_list = mylist[midlist:]

left_list, right_list = sort(left_list), sort(right_list)
return merge(left_list, right_list)

if __name__ == '__main__':
l = sample_list(10, 1000)
print 'Unsorted list'
print l
print '\nSorted list'
sort(l)
``````

Pretty easy, right? Let me know if you have any comments or questions!