Sorting books

#include <algorithm>
#include <iostream>
#include <queue>
#include <vector>

using namespace std;


int merge(vector<int>& arr, vector<int>& temp, int left, int mid, int right)
{
	int inv_count = 0;

	int i = left;
	int j = mid;
	int 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(vector<int>& arr, vector<int>& temp, int left, int right)
{
	int mid, inv_count = 0;
	if (right > left)
	{
		mid = (right + left)/2;
		inv_count = _mergeSort(arr, temp, left, mid);
		inv_count += _mergeSort(arr, temp, mid+1, right);
		inv_count += merge(arr, temp, left, mid+1, right);
	}

	return inv_count;
}


int countSwaps(vector<int>& v, int n) {
    vector<int> temp (n);
	return _mergeSort(v, temp, 0, n - 1);
}

int main()
{
    int n;
    cin >> n;
    vector<int> numbers (n);
    for (int i = 0; i < n; i++)
    {
        cin >> numbers[i];
    }

    cout << countSwaps(numbers, n) << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: WRONG ANSWER

Test 62

Verdict: WRONG ANSWER

Test 63

Verdict: WRONG ANSWER

Test 64

Verdict: WRONG ANSWER

Test 65

Verdict: WRONG ANSWER

Test 66

Verdict: WRONG ANSWER

Test 67

Verdict: WRONG ANSWER

Test 68

Verdict: WRONG ANSWER

Test 69

Verdict: WRONG ANSWER

Test 70

Verdict: WRONG ANSWER

Test 71

Verdict: ACCEPTED