Hacktoberfest2020/merge sorting.py at main · pythonites/Hacktoberfest2020 · GitHub

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c = 0


def merge(arr):
    if len(arr) > 1:
        mid = len(arr) // 2
        L = arr[:mid]
        R = arr[mid:]

        merge(L)
        merge(R)
        i = j = k = 0
        while i < len(L) and j < len(R):
            if L[i] < R[j]:
                arr[k] = L[i]
                i += 1

            else:
                arr[k] = R[j]
                j += 1
                global c
                c += len(L) - i

            k += 1
        while i < len(L):
            arr[k] = L[i]
            i += 1
            k += 1
            # c += 1
        while j < len(R):
            arr[k] = R[j]
            j += 1
            k += 1
            # c += 1


arr = list(map(int, input().split()))

merge(arr)
print(c)