poj 3928 ping pong 树状数组

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<math.h>
#define maxx 100002
using namespace std;
int a[20022],c[100022],x[100022],n,zuo[100022],you[100022];

int lowbit(int x)
 {
     return x&(-x);
 }

 __int64 sum(int p)
 {
     __int64 ans=0;
     while(p>0)
     {
         ans+=c[p];//printf("i %d   c %d  ans %d
",p,c[p],ans);
         p-=lowbit(p);
     }
     return ans;
 }

 void update(int p)
 {
     while(p<=100010)       //!!!!!!!!!!!!!!!!不是p<=n
     {
         c[p]++;
         p+=lowbit(p);
     }

 }
int main()
{
    int i,j,m,t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(i=1;i<=n;i++)
            scanf("%d",&a[i]);

        memset(c,0,sizeof(c));
        for(i=1;i<=n;i++)
        {
            zuo[i]=sum(a[i]);
            update(a[i]);
        }

        memset(c,0,sizeof(c));
        for(i=n;i>=1;i--)
        {
            you[i]=sum(a[i]);
            update(a[i]);
        }
        long long final=0;
        for(i=1;i<=n;i++)
        {
            final+=(zuo[i]*(n-i-you[i]))+(you[i]*(i-zuo[i]-1));
        }
        printf("%lld
",final);
    }
    return 0;
}