結果

問題 No.1740 Alone 'a'
ユーザー milanis48663220
提出日時 2021-11-12 22:37:20
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 52 ms / 2,000 ms
コード長 3,765 bytes
コンパイル時間 1,073 ms
コンパイル使用メモリ 121,192 KB
最終ジャッジ日時 2025-01-25 17:12:55
ジャッジサーバーID
（参考情報） 		judge3 / 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 * 38
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 #
プレゼンテーションモードにする

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>
#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
using namespace std;
typedef long long ll;
template<typename T>
vector<vector<T>> vec2d(int n, int m, T v){
    return vector<vector<T>>(n, vector<T>(m, v));
}
template<typename T>
vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){
    return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v)));
}
template<typename T>
void print_vector(vector<T> v, char delimiter=' '){
    if(v.empty()) {
        cout << endl;
        return;
    }
    for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter;
    cout << v.back() << endl;
}
const ll MOD = 998244353;
class ModInt{
    public:
    ll v;
    ModInt(ll _v = 0){
        if(_v < 0) _v = (_v%MOD)+MOD;
        if(_v >= MOD) _v %= MOD;
        v = _v;
    }
    ModInt operator+(ll n){
        return ModInt((v+n)%MOD);
    }
    ModInt operator-(ll n){
        return ModInt((v-n+MOD)%MOD);
    }
    ModInt operator*(ll n){
        if(n >= MOD) n %= MOD;
        return ModInt((v*n)%MOD);
    }
    ModInt operator/(ll n){
        return ModInt((ModInt(n).inv()*v).v%MOD);
    }
    void operator+=(ll n){
        v = (v+n)%MOD;
    }
    void operator-=(ll n){
        v = (v-n+MOD)%MOD;
    }
    void operator*=(ll n){
        v = (v*n+MOD)%MOD;
    }
    
    
    ModInt operator+(ModInt n){
        return ModInt((v+n.v)%MOD);
    }
    ModInt operator-(ModInt n){
        return ModInt((v-n.v+MOD)%MOD);
    }
    ModInt operator*(ModInt n){
        return ModInt((v*n.v)%MOD);
    }
    ModInt operator/(ModInt n){
        return ModInt((n.inv()*v).v%MOD);
    }
    void operator+=(ModInt n){
        v = (v+n.v)%MOD;
    }
    void operator-=(ModInt n){
        v = (v-n.v+MOD)%MOD;
    }
    void operator*=(ModInt n){
        v = (v*n.v)%MOD;
    }
    void operator=(ModInt n){
        v = n.v;
    }
    bool operator==(ModInt n){
        return v == n.v;
    }
    bool operator!=(ModInt n){
        return v != n.v;
    }
    void operator=(ll n){
        v = n%MOD;
    }
    ModInt inv(){
        if(v == 1) return ModInt(1);
        else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD);
    }
};
ostream& operator<<(ostream& os, const ModInt& m){
    os << m.v;
    return os;
}
istream & operator >> (istream &in,  ModInt &m){
    in >> m.v;
    return in;
}
using mint = ModInt;
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n; string s; cin >> n >> s;
    auto dp = vec3d(n+1, 2, 2, mint(0));
    dp[0][0][0] = 1;
    for(int i = 0; i < n; i++){
        int x = s[i]-'a'+1;
        // 00 -> a
        if(s[i] == 'a') dp[i+1][0][1] += dp[i][0][0];
        else dp[i+1][1][1] += dp[i][0][0];
        // 00 -> a以外
        if(s[i] != 'a'){
            dp[i+1][1][0] += dp[i][0][0]*(x-2);
            dp[i+1][0][0] += dp[i][0][0];
        }
        // 01
        if(s[i] != 'a'){
            dp[i+1][1][1] += dp[i][0][1]*(x-2);
            dp[i+1][0][1] += dp[i][0][1];
        }
        // 10
        dp[i+1][1][0] += dp[i][1][0]*25;
        dp[i+1][1][1] += dp[i][1][0];
        // 11
        dp[i+1][1][1] += dp[i][1][1]*25;
    }
    cout << dp[n][1][1] << endl;
}
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