結果

問題 No.2327 Inversion Sum
コンテスト
ユーザー umimel
提出日時 2023-06-04 05:54:28
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 37 ms / 2,000 ms
コード長 5,234 bytes
コンパイル時間 2,329 ms
コンパイル使用メモリ 185,728 KB
実行使用メモリ 10,880 KB
最終ジャッジ日時 2024-12-29 03:24:14
合計ジャッジ時間 4,090 ms
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 * 30
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;
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 << 60;
const int IINF = 1 << 30 - 1;

template<typename T> struct Edge{
    int to; T w;
    Edge(int to_, T w_=1){
        to = to_;
        w=w_;
    }
};
template<typename T> using Tree = vector<vector<Edge<T>>>;
template<typename T> using Graph = vector<vector<Edge<T>>>;
/* 容量&重み付きエッジ for Dinic */
template<typename T> struct REdge{
    int to;
    T cap;
    T cost;
    int rev;
    REdge(int to_, T cap_, T cost_=1){
        to = to_;
        cap = cap_;
        cost = cost_;
    }
    
    REdge(int to_, T cap_, T cost_, int rev_){
        to = to_;
        cap = cap_;
        cost = cost_;
        rev = rev_;
    }
};

/* 残余グラフ for Dinic */
template<typename T> using RGraph = vector<vector<REdge<T>>>;

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>;

struct SegmentTree{
    ll n;
    vector<ll> dat;

    SegmentTree(ll n_){
        n = 1;
        while(n < n_) n*=2;
        dat.resize(2*n, 0);
    }

    void update(ll k, ll a){
        k += n-1;
        dat[k] += a;
        while(k > 0){
            k = (k-1)/2;
            dat[k] = dat[2*k+1]+dat[2*k+2];
        }
    }

    // the minimun element of [a, b)
    ll query(ll a, ll b){return query_sub(a, b, 0, 0, n);}

    ll query_sub(ll a, ll b, ll k, ll l, ll r){
        if(r <= a || b <= l){
            return 0;
        }else if(a <= l && r <= b){
            return dat[k];
        }else{
            ll vl = query_sub(a, b, 2*k+1, l, (l+r)/2);
            ll vr = query_sub(a, b, 2*k+2, (l+r)/2, r);
            return vl+vr;
        }
    }
};

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    ll n, m; cin >> n >> m;
    ll rn = n-m;
    vector<ll> p(n, -1);
    vector<bool> check(n, false);
    vector<pll> reserve(m);
    rep(i, m){
        ll v, k; cin >> v >> k;
        v--; k--;
        p[k] = v;
        check[v] = true;
        reserve[i] = {k, v};
    }

    vector<ll> lv(n, 0), rv(n, 0);
    if(p[0]==-1) lv[0]++;
    for(ll i=1; i<n; i++) lv[i] = lv[i-1]+(p[i]==-1);
    if(p[n-1]==-1) rv[n-1]++;
    for(ll i=n-2; i>=0; i--) rv[i] = rv[i+1]+(p[i]==-1);

    vector<ll> g_cnt(n, 0), l_cnt(n, 0);
    l_cnt[0] = !check[0];
    for(ll i=1; i<n; i++) l_cnt[i] = l_cnt[i-1]+!check[i];
    g_cnt[n-1] = !check[n-1];
    for(ll i=n-2; i>=0; i--) g_cnt[i] = g_cnt[i+1]+!check[i];

    vector<mint> perm(n+1, 1);
    for(ll i=1; i<=n; i++) perm[i] = perm[i-1]*i;
    
    mint ans = perm[rn]*rn*(rn-1)/4;
    rep(i, n) if(p[i]!=-1){
        ans += perm[rn-1]*g_cnt[p[i]]*lv[i];
        ans += perm[rn-1]*l_cnt[p[i]]*rv[i];
    }

    sort(all(reserve));
    ll original_inv = 0;
    SegmentTree ST(n);
    rep(i, m){
        ll v = reserve[i].se;
        original_inv += ST.query(v+1, n);
        ST.update(v, 1);
    }

    ans += perm[rn]*original_inv;

    cout << ans << endl;
}
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