Counting Inversions

Counting_Inversions.py

f = open("IntegerArray.txt")
a = []
for line in f:
    a.append(int(line))


def handle(t1, t2):
    a1 = t1
    a2 = t2
    result = []
    cnt = 0
    while len(a1) + len(a2) != 0:
        if len(a1) == 0:
            result.append(a2[0])
            a2 = a2[1:]
            cnt += len(a1)
        elif len(a2) == 0:
            result.append(a1[0])
            a1 = a1[1:]
        elif a1[0] > a2[0]:
            result.append(a2[0])
            a2 = a2[1:]
            cnt += len(a1)
        else:
            result.append(a1[0])
            a1 = a1[1:]
    return result, cnt


def count(array):
    if len(array) == 1:
        return array, 0

    first, fc = count(array[:len(array) / 2])
    last, lc = count(array[len(array) / 2:])
    at, cnt = handle(first, last)
    return at, fc + lc + cnt


a, n = count(a)
print n