Untitled

#include <bits/stdc++.h>
using namespace std;

int merge(int arr[], int temp[], int left, int mid, int right)
{
    int i, j, k;
    int inv_count = 0;
    i = left;
    j = mid;
    k = left;
    while ((i <= mid - 1) && (j <= right))
    {
        if (arr[i] <= arr[j])
        {
            temp[k++] = arr[i++];
        }
        else
        {
            temp[k++] = arr[j++];
            inv_count = inv_count + (mid - i);
        }
    }

    while (i <= mid - 1)
    {
        temp[k++] = arr[i++];
    }

    while (j <= right)
    {
        temp[k++] = arr[j++];
    }

    for (i = left; i <= right; i++)
    {
        arr[i] = temp[i];
    }
    return inv_count;
}

int mergeSort(int arr[], int temp[], int left, int right)
{
    int mid;
    int cnt1 =0, cnt2 = 0, cnt3 =0;
    if (right > left)
    {
        mid = (right + left) / 2;

        cnt1 += mergeSort(arr, temp, left, mid);
        cnt2 += mergeSort(arr, temp, mid + 1, right);

        cnt3 += merge(arr, temp, left, mid + 1, right);
    }
    return (cnt1 + cnt2 + cnt3);
}

int inversionCount(int arr[], int array_size)
{
    int temp[array_size];
    return mergeSort(arr, temp, 0, array_size-1);
}
int main()
{
    int arr[] = { 2,4,1,3,5};
    int arr_size = sizeof(arr) / sizeof(arr[0]);
    int inversionCnt = inversionCount(arr, arr_size);
    cout<<" Number of inversions are: "<<inversionCnt;
    return 0;
}