【bzoj4240】有趣的家庭菜园

只要统计每一个左右分别有多少比他高的去min，然后求和

#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>
using namespace std;

typedef long long LL;

#define lowbit(x) (x & (-x))
#define N 300010

struct Node
{
    int h,id;
}a[N];

int n;
int cnt;
LL ans;

int c[N];

int read()
{
    int x=0;
    char ch=getchar();
    while (ch<'0' || ch>'9')
        ch=getchar();
    while (ch>='0' && ch<='9')
    {
        x=x*10+ch-'0';
        ch=getchar();
    }
    return x;
}  

bool cmp(Node x,Node y)
{
    return x.h>y.h;
}

void add(int x)
{
    while (x<=n)
        c[x]++,x+=lowbit(x);
}

int query(int x)
{
    int res(0);
    while (x)
        res+=c[x],x-=lowbit(x);
    return res;
}

int main()
{
    n=read();
    for (int i=1;i<=n;i++)
        a[i].h=read(),a[i].id=i;
    sort(a+1,a+n+1,cmp);
    int k=1;
    for (int i=1;i<=n;i++)
    {
        if (a[i].h!=a[i-1].h)
            while (k<i)
                add(a[k++].id);
        cnt=query(a[i].id);
        ans+=min(cnt,k-1-cnt);
    }
    printf("%lld",ans);
    return 0;
}