LA 4329 - Ping pong

#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
const int Tmax=20005,Tmax2=100005;
int n,data[Tmax],left[Tmax],right[Tmax],num[Tmax2],len;
int lowbit(int x)
{
return x&(-x);
}
int sum(int x)
{
int ret=0;
while(x>0)
{
ret+=num[x];
x-=lowbit(x);
}
return ret;
}
void add(int x,int d)
{
while(x<=len)
{
num[x]+=d;
x+=lowbit(x);
}
return;
}
void tree_array(int start,int end,int move,int *array)
{
int i;
end+=move;
for(i=start;i!=end;i+=move)
{
add(data[i],1);
array[i]=sum(data[i]-1);
}
return;
}
int main()
{
int T,i;
long long int ans;
scanf("%d",&T);
while(T--)
{
ans=0;len=0;
scanf("%d",&n);
for(i=1;i<=n;i++){
scanf("%d",&data[i]);
left[i]=right[i]=0;
len=max(len,data[i]);
}
memset(num,0,sizeof(num));
tree_array(1,n,1,left);
memset(num,0,sizeof(num));
tree_array(n,1,-1,right);
for(i=1;i<=n;i++)
ans+=left[i]*(n-i-right[i])+(i-1-left[i])*right[i];
printf("%lld\n",ans);
}
return 0;
}