#1178432 (C++17) No.3635 Probability trip

• 問題: No.3635 Probability trip
• ユーザー: GOTKAKO
• 提出日時: 2026-08-22 16:13:26
• 言語: C++17 (gcc 15.2.0 + boost 1.90.0)
• 結果: AC
• 実行時間: 73 ms / 2,000 ms
• コード長: 3,982 bytes
• コンパイル時間: 1,770 ms
• コンパイル使用メモリ: 226,900 KB
• 実行使用メモリ: 5,888 KB
• 最終ジャッジ日時: 2026-08-22 16:13:32
• 合計ジャッジ時間: 5,218 ms
• ジャッジサーバーID （参考情報）: judge2_0 / judge3_0

ファイルパターン	結果
sample	AC * 3
other	AC * 43

ソースコード

#include <bits/stdc++.h>
using namespace std;

//入力が必ず-mod<=a<modの時.
template<const int mod> //mod<2^30.
struct modint{ //mod変更が不可能.
    public:
    long long v;
    static void setmod(int m){} //飾り.
    static constexpr long long getmod(){return mod;}
    modint():v(0){}
    template<typename T>
    modint(T a):v(a){if(v < 0) v += mod;}
    long long val()const{return v;}
 
    modint &operator=(const modint &b) = default;
    modint &operator+()const{return (*this);}
    modint operator-()const{return modint(0)-(*this);}
    modint operator+(const modint b)const{return modint(v)+=b;}
    modint operator-(const modint b)const{return modint(v)-=b;}
    modint operator*(const modint b)const{return modint(v)*=b;}
    modint operator/(const modint b)const{return modint(v)/=b;}
    modint &operator+=(const modint b){
        v += b.v; if(v >= mod) v -= mod;
        return *this;
    }
    modint &operator-=(const modint b){
        v -= b.v; if(v < 0) v += mod; 
        return *this;
    }   
    modint &operator*=(const modint b){v = v*b.v%mod; return *this;}
    modint &operator/=(modint b){ //b!=0 mod素数が必須.
        assert(b.v != 0);
        (*this) *= b.pow(mod-2);
        return *this;
    }
    modint pow(long long n)const{
        modint ret = 1,p = v;
        if(n < 0) p = p.inv(),n = -n;
        while(n){
            if(n&1) ret *= p;
            p *= p; n >>= 1;
        }
        return ret;
    }
    modint inv()const{return pow(mod-2);} //素数mod必須.
 
    modint &operator++(){*this += 1; return *this;}
    modint &operator--(){*this -= 1; return *this;}
    modint operator++(int){modint ret = *this; *this += 1; return ret;}
    modint operator--(int){modint ret = *this; *this -= 1; return ret;}
    friend bool operator==(const modint a,const modint b){return a.v==b.v;}
    friend bool operator!=(const modint a,const modint b){return a.v!=b.v;}
    friend bool operator<(const modint a,const modint b){return a.v<b.v;}
    friend bool operator<=(const modint a,const modint b){return a.v<=b.v;}
    friend bool operator>=(const modint a,const modint b){return a.v>=b.v;}
    friend bool operator>(const modint a,const modint b){return a.v>b.v;}
    friend ostream &operator<<(ostream &os,const modint a){return os<<a.v;}
    friend istream &operator>>(istream &is,modint &a){ //入力はmodをとってくれる.
        long long x; is >> x; x %= mod;
        a = modint(x); return is;
    }
};
using mint = modint<998244353>; const long long mod = 998244353;

template<typename T>
vector<vector<T>> multima(vector<vector<T>> &A,vector<vector<T>> &B){
    assert(A.at(0).size() == B.size() && B.size());
    int H = A.size(),W = B.at(0).size();
    vector<vector<T>> ret(H,vector<T>(W));
    for(int i=0; i<H; i++) for(int k=0; k<W; k++){
        for(int l=0; l<A.at(i).size(); l++){
            ret.at(i).at(k) += A.at(i).at(l)*B.at(l).at(k);
        }
    }
    return ret; //計算できる行列のみ.
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N,M; cin >> N >> M;
    vector<vector<int>> Graph(N);
    for(int i=0; i<M; i++){
        int u,v; cin >> u >> v;
        u--; v--;
        Graph.at(u).push_back(v);
        Graph.at(v).push_back(u);
    }    
    vector<vector<mint>> A(N,vector<mint>(N)),B = A;
    A.at(0).at(0) = 1;
    for(int i=0; i<N; i++){
        int n = Graph.at(i).size();
        for(auto to : Graph.at(i)) B.at(i).at(to) = mint(1)/n;
    }

    long long S,T; cin >> S >> T,S--,T--;
    int a,b; cin >> a >> b,a--,b--;
    S -= T;
    auto B2 = B;
    while(T){
        if(T&1) A = multima(A,B2);
        B2 = multima(B2,B2),T >>= 1;
    }
    for(int i=1; i<N; i++) A.at(i).at(i) = A.at(0).at(i),A.at(0).at(i) = 0;
    B2 = B;
    while(S){
        if(S&1) A = multima(A,B2);
        B2 = multima(B2,B2),S >>= 1;
    }
    mint sum = 0;
    for(int i=0; i<N; i++) sum += A.at(i).at(a);
    cout << A.at(b).at(a)/sum << endl;
}