結果
問題 | No.2068 Restricted Permutation |
ユーザー |
👑 ![]() |
提出日時 | 2022-09-02 21:59:44 |
言語 | C++17(gcc12) (gcc 12.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 54 ms / 2,000 ms |
コード長 | 2,221 bytes |
コンパイル時間 | 2,406 ms |
コンパイル使用メモリ | 114,264 KB |
最終ジャッジ日時 | 2025-02-07 01:13:47 |
ジャッジサーバーID (参考情報) |
judge5 / judge2 |
(要ログイン)
ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 23 |
ソースコード
#line 1 "Main.cpp"#include <iostream>#include <string>#include <vector>#include <algorithm>#include <atcoder/modint>#line 2 "nachia\\math\\combination.hpp"#line 4 "nachia\\math\\combination.hpp"namespace nachia{template<class Modint>class Comb{private:::std::vector<Modint> F;::std::vector<Modint> iF;public:Comb(int n){F.assign(n+1, Modint(1));for(int i=1; i<=n; i++) F[i] = F[i-1] * Modint(i);iF.assign(n+1, Modint(1));iF[n] = F[n].inv();for(int i=n; i>=1; i--) iF[i-1] = iF[i] * Modint(i);}Modint factorial(int n) const { return F[n]; }Modint inv_factorial(int n) const { return iF[n]; }Modint inv_of(int n) const { return iF[n] * F[n-1]; }Modint comb(int n, int r) const {if(n < 0 || n < r || r < 0) return Modint(0);return F[n] * iF[r] * iF[n-r];}Modint inv_comb(int n, int r) const {if(n < 0 || n < r || r < 0) return Modint(0);return iF[n] * F[r] * F[n-r];}Modint perm(int n, int r) const {if(n < 0 || n < r || r < 0) return Modint(0);return F[n] * iF[n-r];}Modint inv_perm(int n, int r) const {if(n < 0 || n < r || r < 0) return Modint(0);return iF[n] * F[n-r];}Modint operator()(int n, int r) const { return comb(n,r); }};} // namespace nachia#line 8 "Main.cpp"using namespace std;using i32 = int32_t;using u32 = uint32_t;using i64 = int64_t;using u64 = uint64_t;#define rep(i,n) for(int i=0; i<(int)(n); i++)using modint = atcoder::static_modint<998244353>;int main(){int N,K,X; cin >> N >> K >> X;K--; X--;if(N == 1){ cout << X << endl; return 0; }int R = N-K-1;nachia::Comb<modint> comb(N);modint ans = 0;rep(i,N-1) ans += modint(i) / 2 * comb.factorial(i + ((R<=i)?1:0));ans += modint(X) / (N-1) * R * comb.factorial(R);for(int i=0; i<K; i++) ans += modint(N-1-X) / (N-1) * comb.factorial(N-1-i);ans *= comb.factorial(N-1);cout << ans.val() << endl;return 0;}struct ios_do_not_sync{ios_do_not_sync(){std::ios::sync_with_stdio(false);std::cin.tie(nullptr);}} ios_do_not_sync_instance;