牛客练习赛7E 珂朵莉的数列

#include<bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define mp make_pair
#define pb push_back
#define mod 1000000007
#define pii pair<int,int>
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
 
using namespace std;
 
const int g=10.0,eps=1e-9;
const int N=1000000+10,maxn=5000000+10,inf=0x3f3f3f3f;
 
ll a[N],b[N],sum[N];
void add(int i,ll x)
{
    while(i<N)
    {
        sum[i]+=x;
        i+=i&(-i);
    }
}
ll query(int i)
{
    ll ans=0;
    while(i>0)
    {
        ans+=sum[i];
        i-=i&(-i);
    }
    return ans;
}
int main()
{
    /*ios::sync_with_stdio(false);
    cin.tie(0);*/
    ll n,cnt=0;
    scanf("%lld",&n);
    for(ll i=1;i<=n;i++)scanf("%lld",&a[i]),b[cnt++]=a[i];
    sort(b,b+cnt);
    cnt=unique(b,b+cnt)-b;
    for(ll i=1;i<=n;i++)a[i]=lower_bound(b,b+n,a[i])-b,a[i]++;
    ll ans[2]={0},te=1e18;
    for(ll i=1;i<=n;i++)
    {
        ans[0]+=(ll)(n-i+1)*(query(n)-query(a[i]));
        if(ans[0]>=te)ans[1]+=ans[0]/te,ans[0]%=te;
        add(a[i],i);
    }
    if(ans[1])printf("%lld%018lld\n",ans[1],ans[0]);
    else printf("%lld\n",ans[0]);
    return 0;
}
/*******************
3
0 0 0
*******************/