結果

問題 No.2616 中央番目の中央値
ユーザー umimel
提出日時 2024-01-26 21:51:18
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 280 ms / 2,000 ms
コード長 4,053 bytes
コンパイル時間 1,911 ms
コンパイル使用メモリ 175,832 KB
実行使用メモリ 10,864 KB
最終ジャッジ日時 2024-09-28 08:03:10
合計ジャッジ時間 7,670 ms
ジャッジサーバーID
(参考情報)
judge3 / judge1
このコードへのチャレンジ
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ファイルパターン 結果
other AC * 37
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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;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
const ll MOD1000000007 = 1000000007;
const ll MOD998244353 = 998244353;
const ll MOD[3] = {999727999, 1070777777, 1000000007};
const ll LINF = 1LL << 60LL;
const int IINF = (1 << 30) - 1;
template<typename T, T (*op)(T, T), T (*e)()>
struct segtree{
int n;
vector<T> dat;
segtree(int n_){
n = 1;
while(n < n_) n*=2;
dat.resize(2*n, e());
}
void update(int k, T x){
k += n-1;
dat[k] = x;
while(k > 0){
k = (k-1)/2;
dat[k] = op(dat[2*k+1], dat[2*k+2]);
}
}
// the prod element of [a, b)
T query(int a, int b){return query_sub(a, b, 0, 0, n);}
T query_sub(int a, int b, int k, int l, int r){
if(r <= a || b <= l){
return e();
}else if(a <= l && r <= b){
return dat[k];
}else{
T vl = query_sub(a, b, 2*k+1, l, (l+r)/2);
T vr = query_sub(a, b, 2*k+2, (l+r)/2, r);
return op(vl, vr);
}
}
};
template<long long mod>
class modint{
long long x;
public:
modint(long long x=0) : x((x%mod+mod)%mod) {}
modint operator-() const {
return modint(-x);
}
bool operator==(const modint& a){
if(x == a) return true;
else return false;
}
bool operator==(long long a){
if(x == a) return true;
else return false;
}
bool operator!=(const modint& a){
if(x != a) return true;
else return false;
}
bool operator!=(long long a){
if(x != a) return true;
else return false;
}
modint& operator+=(const modint& a) {
if ((x += a.x) >= mod) x -= mod;
return *this;
}
modint& operator-=(const modint& a) {
if ((x += mod-a.x) >= mod) x -= mod;
return *this;
}
modint& operator*=(const modint& a) {
(x *= a.x) %= mod;
return *this;
}
modint operator+(const modint& a) const {
modint res(*this);
return res+=a;
}
modint operator-(const modint& a) const {
modint res(*this);
return res-=a;
}
modint operator*(const modint& a) const {
modint res(*this);
return res*=a;
}
modint pow(long long t) const {
if (!t) return 1;
modint a = pow(t>>1);
a *= a;
if (t&1) a *= *this;
return a;
}
// for prime mod
modint inv() const {
return pow(mod-2);
}
modint& operator/=(const modint& a) {
return (*this) *= a.inv();
}
modint operator/(const modint& a) const {
modint res(*this);
return res/=a;
}
friend std::istream& operator>>(std::istream& is, modint& m) noexcept {
is >> m.x;
m.x %= mod;
if (m.x < 0) m.x += mod;
return is;
}
friend ostream& operator<<(ostream& os, const modint& m){
os << m.x;
return os;
}
};
using mint = modint<MOD998244353>;
int op(int a, int b){
return a+b;
}
int e(){
return 0;
}
void solve(){
int n; cin >> n;
vector<int> p(n);
for(int i=0; i<n; i++){
cin >> p[i];
p[i]--;
}
vector<mint> fac(n+1, 1);
for(int i=1; i<=n; i++) fac[i] = fac[i-1]*mint(i);
segtree<int, op, e> seg(n);
mint ans = 0;
for(int i=0; i<n; i++){
int lx = seg.query(0, p[i]);
int ly = i-lx;
int rx = p[i]-lx;
int ry = n-lx-ly-rx-1;
ans += fac[lx+ry]/(fac[lx]*fac[ry])*fac[rx+ly]/(fac[rx]*fac[ly]);
seg.update(p[i], 1);
}
cout << ans << '\n';
}
int main(){
cin.tie(nullptr);
ios::sync_with_stdio(false);
int T=1;
//cin >> T;
while(T--) solve();
}
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