树状数组---区间更新（差分数组实现）

/*
* @Author: Achan
* @Date:   2018-10-28 12:55:01
* @Last Modified by:   Achan
* @Last Modified time: 2018-10-28 19:59:13
*/
#include
#include
#include
#include
#include
#include
#include 
#include
#include 
using namespace std;
 
#define X           first
#define Y           second
#define eps         1e-2
#define gcd         __gcd
#define pb          push_back
#define PI          acos(-1.0)
#define lowbit(x)   (x)&(-x)
#define fin         freopen("in.txt","r",stdin);
#define fout        freopen("out.txt","w",stdout);
#define bug         printf("!!!!!\n");
#define mem(x,y)    memset(x,y,sizeof(x))
#define rep(i,j,k)  for(int i=j;i<(int)k;i++)
#define per(i,j,k)  for(int i=j;i<=(int)k;i++)
#define pset(x)     setiosflags(ios::fixed)<
#define io std::ios::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL);
 
typedef long long ll;
typedef long double LD; 
typedef pair<int,int> pii;
typedef unsigned long long ull; 
 
const int inf  = 1<<30;
const ll  INF  = 1e18 ;
const int mod  = 1e9+7;
const int maxn = 1e5+2;
const int mov[4][2] = {-1,0,1,0,0,1,0,-1};
const int Mov[8][2] = {-1,-1,-1,0,-1,1,0,-1,0,1,1,-1,1,0,1,1};
  
inline int read(){
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
 
 
int a[maxn];
bool vis[maxn];
int c[maxn];  //保存排名信息
int n;
double rak[maxn];
int tree[maxn],tree1[maxn];

inline void update(int *c,int x, int val)
{
	while(x<=n)
	{
		c[x] += val;
		x += (x& -x);
	}
}
inline int getsum(int *c,int x) 
{
	int sum = 0;
	while(x>0)
	{
		sum += c[x];
		x -= x&(-x);
	}
	return sum;

}
int main(void)
{
    //fin
    //fout 
    io 
    int T;cin>>T;
    while(T--)
    {
        cin>>n;
        memset(tree,0,sizeof(tree));
        memset(tree1,0,sizeof(tree1));
        for(int i=1; i<=n;i++) 
    	{
    		cin>>a[i];
    		update(tree,a[i],1); //起始
    		update(tree,n+1,-1); //末尾
    		update(tree1,a[i],1*(a[i]-1)); //起始
    		update(tree1,n+1, -1*n); 	//末尾
    		int x,y;
            x=y=a[i];
            rak[a[i]] = (y*getsum(tree,y)-(x-1)*getsum(tree,x-1))-(getsum(tree1,y)-getsum(tree1,x-1)) ;
    	}

    	// for(int i=1;i<=n; i++) cout<

        for(int i=1;i<=n;i++)
        {
              
            double rank = rak[a[i]]; 
 			double ex = (double)rank/(1.0 * i); 
            double bex = 1.0 /(double)(n-i);  
            // cout<<"rank  "<
            if(ex < bex)  
            {
                cout<<a[i]<<endl;
                break; 
            }
            // else if(ex==bex)
            // {
            //     cout<
            //     break;
            // }
        }
 
     //printf("Case %d: ",cas++);
     //cout<<"Case #"<
    }
 
 
 
 
 
     
 #ifdef LOCAL
    Debug("My Time: %.3lfms\n", (double)clock() / CLOCKS_PER_SEC);
#endif   
}