結果

問題 No.271 next_permutation (2)
ユーザー msm1993msm1993
提出日時 2020-11-12 09:23:21
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 21 ms / 2,000 ms
コード長 2,929 bytes
コンパイル時間 1,940 ms
コンパイル使用メモリ 174,780 KB
実行使用メモリ 7,040 KB
最終ジャッジ日時 2024-07-22 19:04:21
合計ジャッジ時間 2,228 ms
ジャッジサーバーID
(参考情報)
judge5 / judge3
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
other AC * 21
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T> V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " "
    ;} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out
    << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T> mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out <<
    it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }
struct BIT {
ll N;
vector<ll> bit;
BIT(ll N):N(N) {
bit.resize(N + 1, 0);
}
void add(ll x, ll val){
while (x <= N) {
bit[x] += val;
x += x & -x;
}
}
ll sum(ll x){
ll ret = 0;
while (x) {
ret += bit[x];
x &= (x - 1);
}
return (ret);
}
};
const ll MOD = 1e9+7;
struct FNS{
vector<ll> F;
vector<ll> fact;
ll Inv[5];
FNS(vector<ll> permutation):F(permutation.size()),fact(permutation.size()+5){
BIT bit(permutation.size());
fact[0] = 1;
for(ll i = 1; i < fact.size();i++) fact[i] = i*fact[i-1]%MOD;
Inv[0] = 0; Inv[1] = 1;
for(int i = 2; i < 5;i++) Inv[i] = Inv[MOD%i] * (MOD - MOD/i) % MOD;
for(int i = (int)permutation.size()-1; i >= 0; i--){
F[i] = bit.sum(permutation[i]);
bit.add(permutation[i],1);
}
}
ll add(ll K){
for(ll i = 0; i < F.size();i++){
ll T = K+F[F.size()-1-i];
F[F.size()-1-i]=T%(i+1); K=T/(i+1);
}
return K;
}
ll invsum(){
ll ret = 0;
ll t1 = 0,t2 = 1;
for(ll i = F.size()-1; i >= 0; i--){
ll n = F.size()-1-i;
(ret+=F[i]*fact[n]%MOD*n%MOD*(n-1+MOD)%MOD*Inv[4]%MOD)%=MOD;
(ret+=t2*F[i]%MOD*(F[i]-1+MOD)%MOD*Inv[2]%MOD)%=MOD;
(ret+=F[i]*t1%MOD)%=MOD;
(t1+=F[i]*t2%MOD)%=MOD;
(t2*=(F.size()-i+MOD)%MOD)%=MOD;
}
return ret;
}
};
ll solve(){
ll N,K; cin >> N >> K;
vector<ll> p(N);
for(auto& in:p) cin >> in;
FNS fns(p);
ll linv = fns.invsum();
ll mul = fns.add(K);
ll rinv = fns.invsum();
ll res = 0;
res = mul*fns.fact[N]%MOD*N%MOD*(N-1+MOD)%MOD*fns.Inv[4]%MOD + (rinv - linv + MOD)%MOD;
res %= MOD;
return res;
}
int main(void) {
cin.tie(0); ios_base::sync_with_stdio(false);
cout << solve() << endl;
return 0;
}
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
0