Cod sursa(job #3224972)

Utilizator Dragono63Stanciu Rares Stefan Dragono63 Data 16 aprilie 2024 18:08:36
Problema P-sir Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 2.68 kb
#ifndef LOCAL
    #pragma GCC optimize("O3")
    #pragma GCC target("avx2")
#endif

#ifdef LOCAL
    #define _GLIBCXX_DEBUG
#endif

#include <bits/stdc++.h>
#define pb push_back
#define pii pair<int, int>
using ll = long long;
using ci = const int;
using uint = unsigned int;
using cll = const long long;

#define int uint
using namespace std;

const int NMAX = 2e3 + 5;
/*******************************/
// INPUT / OUTPUT

#ifndef LOCAL
    ifstream in("psir.in");
    ofstream out("psir.out");
    #define cin in
    #define cout out
#endif
/*******************************/
/// GLOBAL DECLARATIONS

int N, M;
int sol;
int v[NMAX];

struct AIB
{
    int n;
    vector <int> data;

    AIB(){}

    AIB(int _n)
    {
        n = _n;
        data.resize(n + 1, 0);
    }

    inline void update(int pos, int val)
    {
        while (pos <= n)
        {
            data[pos] += val;
            pos += (pos & (-pos));
        }
    }

    inline int query(int pos)
    {
        int suma = 0;
        while (pos)
        {
            suma += data[pos];
            pos -= (pos & (-pos));
        }

        return suma;
    }
};

vector <int> valori;
vector <AIB> aib;
/*******************************/
/// FUNCTIONS

void ReadInput();
void Solution();
void Output();
/*******************************/
///-------------------------------------
inline void ReadInput()
{
    cin >> N;

    for (int i = 0 ; i < N ; ++ i)
    {
        cin >> v[i];
        valori.push_back(v[i]);
    }
}
///-------------------------------------
inline int get_norm(int x)
{
    return lower_bound(valori.begin(), valori.end(), x) - valori.begin() + 1;
}
///-------------------------------------
inline void Solution()
{
    sort(valori.begin(), valori.end());
    valori.erase(unique(valori.begin(), valori.end()), valori.end());

    M = valori.size();
    aib.resize(N);
    for (int i = 0 ; i < N ; ++ i)
    {
        aib[i] = AIB(M);
        v[i] = get_norm(v[i]);
    }

    int dp;
    for (int i = 0 ; i < N ; ++ i)
    {
        for (int j = i + 1 ; j < N ; ++ j)
        {
            dp = 1;
            if (v[i] > v[j])
            {
                dp += aib[i].query(v[j] - 1);
            }
            else
            {
                if (v[i] < v[j])
                    dp += (aib[i].query(valori.size()) - aib[i].query(v[j]));
            }

            sol += dp;
            aib[j].update(v[i], dp);
        }
    }
}
///-------------------------------------
inline void Output()
{
    cout << sol;
}
///-------------------------------------
signed main()
{
    #ifndef LOCAL
        ios::sync_with_stdio(false);
        cin.tie(NULL);
        cout.tie(NULL);
    #endif
    ReadInput();
    Solution();
    Output();
    return 0;
}