結果
問題 | No.2616 中央番目の中央値 |
ユーザー |
👑 |
提出日時 | 2024-01-26 21:58:10 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 293 ms / 2,000 ms |
コード長 | 2,975 bytes |
コンパイル時間 | 4,311 ms |
コンパイル使用メモリ | 258,376 KB |
最終ジャッジ日時 | 2025-02-18 23:13:36 |
ジャッジサーバーID (参考情報) |
judge1 / judge4 |
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ファイルパターン | 結果 |
---|---|
other | AC * 37 |
ソースコード
#include<bits/stdc++.h>#include<atcoder/all>#define rep(i,n) for(int i=0;i<n;i++)using namespace std;using namespace atcoder;typedef long long ll;typedef vector<int> vi;typedef vector<long long> vl;typedef vector<vector<int>> vvi;typedef vector<vector<long long>> vvl;typedef long double ld;typedef pair<int, int> P;ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second; return os;}template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); returnos;}template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : "");return os;}template<typename T> void chmin(T& a, T b){a = min(a, b);}template<typename T> void chmax(T& a, T b){a = max(a, b);}using mint = modint998244353;// combination mod prime// https://youtu.be/8uowVvQ_-Mo?t=6002// https://youtu.be/Tgd_zLfRZOQ?t=9928struct modinv {int n; vector<mint> d;modinv(): n(2), d({0,1}) {}mint operator()(int i) {while (n <= i) d.push_back(-d[mint::mod()%n]*(mint::mod()/n)), ++n;return d[i];}mint operator[](int i) const { return d[i];}} invs;struct modfact {int n; vector<mint> d;modfact(): n(2), d({1,1}) {}mint operator()(int i) {while (n <= i) d.push_back(d.back()*n), ++n;return d[i];}mint operator[](int i) const { return d[i];}} facts;struct modfactinv {int n; vector<mint> d;modfactinv(): n(2), d({1,1}) {}mint operator()(int i) {while (n <= i) d.push_back(d.back()*invs(n)), ++n;return d[i];}mint operator[](int i) const { return d[i];}} ifacts;mint comb(int n, int k) {if (n < k || k < 0) return 0;return facts(n)*ifacts(k)*ifacts(n-k);}using S = int;S op(S a, S b){return a + b;}S e(){return 0;}int main(){int n;cin >> n;vector<int> p(n);cin >> p;rep(i, n) p[i]--;vector<int> s1(n), s2(n), l1(n), l2(n);{segtree<S, op, e> seg(n);rep(i, n){s1[i] = seg.prod(p[i], n);l1[i] = seg.prod(0, p[i]);seg.set(p[i], 1);}}{reverse(p.begin(), p.end());segtree<S, op, e> seg(n);rep(i, n){s2[i] = seg.prod(p[i], n);l2[i] = seg.prod(0, p[i]);seg.set(p[i], 1);}reverse(s2.begin(), s2.end());reverse(l2.begin(), l2.end());reverse(p.begin(), p.end());}mint ans = 0;rep(i, n){// cout << s1[i] << ' ' << l1[i] << ' ' << s2[i] << ' ' << l2[i] << "\n";ans += comb(s1[i] + l2[i], min(s1[i], l2[i])) * comb(s2[i] + l1[i], min(s2[i], l1[i]));}cout << ans << "\n";return 0;}