結果

問題 No.121 傾向と対策：門松列（その２）
コンテスト
ユーザー fumiphys
提出日時 2019-05-11 17:40:33
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 2,594 ms / 5,000 ms
コード長 4,753 bytes
コンパイル時間 1,942 ms
コンパイル使用メモリ 182,720 KB
実行使用メモリ 139,960 KB
最終ジャッジ日時 2024-07-02 01:15:58
合計ジャッジ時間 8,006 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge1
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ファイルパターン 結果
other AC * 9
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ソースコード

diff #
raw source code 

// includes
#include <bits/stdc++.h>

// macros
#define ll long long int
#define pb emplace_back
#define mk make_pair
#define pq priority_queue
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define vrep(v, i) for(int i = 0; i < (v).size(); i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define FI first
#define SE second
#define dump(a, n) for(int i = 0; i < n; i++)cout << a[i] << "\n "[i + 1 != n];
#define dump2(a, n, m) for(int i = 0; i < n; i++)for(int j = 0; j < m; j++)cout << a[i][j] << "\n "[j + 1 != m];
using namespace std;

//  types
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
typedef pair<double, double> Pd;
typedef complex<double> cd;
 
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1e9 + 7;

// solve
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}

template<typename T>
struct BIT_{
  int n;
  vector<T> bit;
  BIT_(int n_){
    n = n_;
    bit = vector<T>(n+1, 0);
  }
  void add(int a, T w){
    for(int x = a; x < n; x |= (x + 1)){
      bit[x] += w;
    }
  }
  T sum(int a){
    T res = 0;
    for(int x = a; x >= 0; x = (x & (x + 1)) - 1){
      res += bit[x];
    }
    return res;
  }
};

typedef struct BIT_<int> BITI;
typedef struct BIT_<long long> BITL;

int li[1000001];
int ri[1000001];
int ld[1000001];
int rd[1000001];

int main(int argc, char const* argv[])
{
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<ll> a(n);
  cin >> a;
  if(n < 3){
    cout << 0 << endl;
    return 0;
  }
  BITI bt(n);
  map<ll, vector<int>> mp;
  rep(i, n)mp[a[i]].pb(i);
  irep(itr, mp){
    vector<int> v = itr->second;
    for(auto e: v){
      ld[e] = bt.sum(e);
      rd[e] = bt.sum(n - 1) - bt.sum(e);
    }
    for(auto e: v)bt.add(e, 1);
  }
  bt = BITI(n);
  for(auto itr = mp.rbegin(); itr != mp.rend(); ++itr){
    //rep(i, n)cout << bt.sum(i) - (i>0?bt.sum(i-1):0) << "\n "[i+1!=n];
    vector<int> v = itr->second;
    for(auto e: v){
      //cerr << e << " " << bt.sum(e) << " " << bt.sum(n - 1) << endl;
      li[e] = bt.sum(e);
      ri[e] = bt.sum(n - 1) - bt.sum(e);
    }
    for(auto e: v)bt.add(e, 1);
  }
  //rep(i, n)cout << i << " " << ri[i] << endl;
  ll res = (ll)n * (ll)(n - 1) * (ll)(n - 2) / 6;
  rep(i, n){
    res -= (ll)li[i] * (ll)rd[i];
    res -= (ll)ri[i] * (ll)ld[i];
  }
  irep(itr, mp){
    vector<int> v = itr->second;
    if(sz(v) >= 3){
      res -= (ll)sz(v) * (ll)(sz(v) - 1) * (ll)(sz(v) - 2) / 6;
    }
    if(sz(v) >= 2){
      res -= (ll)(sz(v)) * (ll)(sz(v) - 1) * (ll)(n - sz(v)) / 2;
    }
  }
  cout << res << endl;
  return 0;
}
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