結果
問題 | No.2511 Mountain Sequence |
ユーザー |
|
提出日時 | 2023-10-20 23:51:58 |
言語 | C++14 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 144 ms / 2,000 ms |
コード長 | 3,246 bytes |
コンパイル時間 | 1,733 ms |
コンパイル使用メモリ | 168,580 KB |
実行使用メモリ | 15,608 KB |
最終ジャッジ日時 | 2024-09-21 00:08:26 |
合計ジャッジ時間 | 7,852 ms |
ジャッジサーバーID (参考情報) |
judge2 / judge4 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 32 |
ソースコード
#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 secondmt19937_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<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 modmodint 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>;const ll MAX = 510000;mint fac[MAX], finv[MAX], inv[MAX];void cominit(){fac[0] = fac[1] = 1;finv[0] = finv[1] = 1;inv[1] = 1;for(ll i=2; i<MAX; i++){fac[i] = fac[i-1] * i;inv[i] = mint(i).inv();finv[i] = finv[i-1] * inv[i];}}mint com(ll n, ll k){if(n < k) return 0;if(n < 0 || k < 0) return mint(0);return fac[n] * finv[k] * finv[n-k];}void solve(){ll n, m; cin >> n >> m;mint ans = 0;for(ll j=1; j<=m; j++){if(2*(j-1) < n-1) continue;ans += com(2*(j-1), n-1);}cout << ans << endl;}int main(){cin.tie(nullptr);ios::sync_with_stdio(false);cominit();int T=1;//cin >> T;while(T--) solve();}