OJ-Problems-Source/HDOJ/2492_autoAC.cpp

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#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cstdlib>
#include<algorithm>
using namespace std;
const int top=100100;
struct Num
{
int val,pos;
}num[top];
bool operator<(Num nl,Num nr)
{
return nl.val<nr.val;
}
int order[top],tree[top];
int n,i,leftLess,leftMuch,rightLess,rightMuch;
int lowbit(int x)
{
return x&(-x);
}
void update(int i,int x)
{
while(i<=n)
{
tree[i]+=x;
i+=lowbit(i);
}
}
int query(int i)
{
int ans;
for(ans=0;i>0;i-=lowbit(i))
{
ans+=tree[i];
}
return ans;
}
int main()
{
int t;
__int64 ans;
scanf("%d",&t);
while(t--)
{
scanf("%d",&n);
for(i=1;i<=n;i++)
{
scanf("%d",&num[i].val);
num[i].pos=i;
}
sort(num+1,num+n+1);
order[num[1].pos]=1;
for(i=2;i<=n;i++)
{
if(num[i].val==num[i-1].val)
order[num[i].pos]=order[num[i-1].pos];
else
order[num[i].pos]=i;
}
memset(tree,0,sizeof(tree));
ans=0;
for(i=1;i<=n;i++)
{
update(order[i],1);
leftLess=query(order[i])-1;
leftMuch=i-leftLess-1;
rightLess=order[i]-leftLess-1;
rightMuch=n-order[i]-leftMuch;
ans+=leftLess*rightMuch+leftMuch*rightLess;
}
printf("%I64d\n",ans);
}
return 0;
}