結果

問題 No.1621 Sequence Inversions
コンテスト
ユーザー tokusakurai
提出日時 2021-07-22 22:23:08
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 389 ms / 3,000 ms
コード長 5,417 bytes
コンパイル時間 2,219 ms
コンパイル使用メモリ 213,324 KB
最終ジャッジ日時 2025-01-23 06:58:45
ジャッジサーバーID
（参考情報） 		judge4 / judge2
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
sample AC * 3
other AC * 26
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 # 

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
//const int MOD = 1000000007;
const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

template<int mod>
struct Mod_Int{
    int x;

    Mod_Int() : x(0) {}

    Mod_Int(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    Mod_Int &operator += (const Mod_Int &p){
        if((x += p.x) >= mod) x -= mod;
        return *this;
    }

    Mod_Int &operator -= (const Mod_Int &p){
        if((x += mod - p.x) >= mod) x -= mod;
        return *this;
    }

    Mod_Int &operator *= (const Mod_Int &p){
        x = (int) (1LL * x * p.x % mod);
        return *this;
    }

    Mod_Int &operator /= (const Mod_Int &p){
        *this *= p.inverse();
        return *this;
    }

    Mod_Int &operator ++ () {return *this += Mod_Int(1);}

    Mod_Int operator ++ (int){
        Mod_Int tmp = *this;
        ++*this;
        return tmp;
    }

    Mod_Int &operator -- () {return *this -= Mod_Int(1);}

    Mod_Int operator -- (int){
        Mod_Int tmp = *this;
        --*this;
        return tmp;
    }

    Mod_Int operator - () const {return Mod_Int(-x);}

    Mod_Int operator + (const Mod_Int &p) const {return Mod_Int(*this) += p;}

    Mod_Int operator - (const Mod_Int &p) const {return Mod_Int(*this) -= p;}

    Mod_Int operator * (const Mod_Int &p) const {return Mod_Int(*this) *= p;}

    Mod_Int operator / (const Mod_Int &p) const {return Mod_Int(*this) /= p;}

    bool operator == (const Mod_Int &p) const {return x == p.x;}

    bool operator != (const Mod_Int &p) const {return x != p.x;}

    Mod_Int inverse() const {
        assert(*this != Mod_Int(0));
        return pow(mod-2);
    }

    Mod_Int pow(long long k) const{
        Mod_Int now = *this, ret = 1;
        for(; k > 0; k >>= 1, now *= now){
            if(k&1) ret *= now;
        }
        return ret;
    }

    friend ostream &operator << (ostream &os, const Mod_Int &p){
        return os << p.x;
    }

    friend istream &operator >> (istream &is, Mod_Int &p){
        long long a;
        is >> a;
        p = Mod_Int<mod>(a);
        return is;
    }
};

using mint = Mod_Int<998244353>;

template<int mod, int primitive_root>
struct Number_Theorem_Transform{
    using T = Mod_Int<mod>;
    vector<T> r, ir;

    Number_Theorem_Transform(){
        r.resize(30), ir.resize(30);
        for(int i = 0; i < 30; i++){
            r[i] = -T(primitive_root).pow((mod-1)>>(i+2));
            ir[i] = r[i].inverse();
        }
    }

    void ntt(vector<T> &a, int n) const{
        assert((n&(n-1)) == 0);
        a.resize(n);
        for(int k = n; k >>= 1;){
            T w = 1;
            for(int s = 0, t = 0; s < n; s += 2*k){
                for(int i = s, j = s+k; i < s+k; i++, j++){
                    T x = a[i], y = w*a[j];
                    a[i] = x+y, a[j] = x-y;
                }
                w *= r[__builtin_ctz(++t)];
            }
        }
    }

    void intt(vector<T> &a, int n) const{
        assert((n&(n-1)) == 0);
        a.resize(n);
        for(int k = 1; k < n; k <<= 1){
            T w = 1;
            for(int s = 0, t = 0; s < n; s += 2*k){
                for(int i = s, j = s+k; i < s+k; i++, j++){
                    T x = a[i], y = a[j];
                    a[i] = x+y, a[j] = w*(x-y);
                }
                w *= ir[__builtin_ctz(++t)];
            }
        }
        T inv = T(n).inverse();
        for(auto &e: a) e *= inv;
    }

    vector<T> convolve(vector<T> a, vector<T> b) const{
        int k = (int)a.size()+(int)b.size()-1, n = 1;
        while(n < k) n <<= 1;
        ntt(a, n), ntt(b, n);
        for(int i = 0; i < n; i++) a[i] *= b[i];
        intt(a, n), a.resize(k);
        return a;
    }
};

Number_Theorem_Transform<998244353, 3> NTT;

int main(){
    int N, K; cin >> N >> K;

    map<int, int> mp;
    rep(i, N){
        int A; cin >> A;
        mp[A]++;
    }

    vector<vector<vector<mint>>> dp(N+1, vector<vector<mint>>(N+1, vector<mint>(K+1, 0)));
    rep(j, N+1){
        rep(i, N+1){
            rep(k, K+1){
                if(j == 0){
                    if(k == 0) dp[i][j][k] = 1;
                    continue;
                }
                if(k >= i){
                    dp[i][j][k] += dp[i][j-1][k-i];
                }
                if(i > 0){
                    dp[i][j][k] += dp[i-1][j][k];
                }
            }
        }
    }

    vector<mint> f(K+1, 0);
    f[0] = 1;

    int M = 0;
    each(e, mp){
        f = NTT.convolve(f, dp[M][e.second]);
        f.resize(K+1);
        M += e.second;
    }

    cout << f[K] << '\n';
}
0