poj 1804 Brainman

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>

using namespace std;
typedef long long LL;
const int MAXN = 1010;

int a[MAXN], b[MAXN];
LL sum;

void Merge(int low, int mid, int high)
{
int i = low, j = mid+1, k = low;

while(i <= mid && j <= high)
{
if(a[i] <= a[j])
b[k++] = a[i++];
else
b[k++] = a[j++], sum += (mid - i + 1);
}

while(i <= mid)
b[k++] = a[i++];
while(j <= high)
b[k++] = a[j++];
for(int i = low; i <= high; ++i)
a[i] = b[i];
return ;
}

void Merge_Sort(int low, int high)
{
if(low == high)
return ;
if(low < high)
{
int mid = (low + high) >> 1;
Merge_Sort(low, mid);
Merge_Sort(mid+1, high);
Merge(low, mid, high);
}
return ;
}

int main()
{
int T, kcase = 1;
int n;
scanf("%d", &T);
while(T--)
{
scanf("%d", &n);
for(int i = 0; i < n; ++i)
scanf("%d", &a[i]);
sum = 0;
Merge_Sort(0, n-1);
printf("Scenario #%d:\n%I64d\n\n", kcase++,sum);
}
return 0;
}