week1.py

#!/usr/bin/env python2
count = 0


def merge_sort(li):

    if len(li) < 2:
        return li
    m = len(li) / 2
    return merge(merge_sort(li[:m]), merge_sort(li[m:]))


def merge(l, r):
    global count
    result = []
    i = j = 0
    while i < len(l) and j < len(r):
        if l[i] < r[j]:
            result.append(l[i])
            i += 1
        else:
            result.append(r[j])
            count = count + (len(l) - i)
            j += 1
    result.extend(l[i:])
    result.extend(r[j:])
    return result

with open('./data1.txt', 'r') as f:
    lines = f.readlines()
    unsorted = map(int, lines)


merge_sort(unsorted)
print count