結果

問題 No.1646 Avoid Palindrome
ユーザー ebi_fly
提出日時 2021-08-13 22:11:47
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 184 ms / 3,000 ms
コード長 5,479 bytes
コンパイル時間 3,972 ms
コンパイル使用メモリ 195,772 KB
最終ジャッジ日時 2025-01-23 19:38:35
ジャッジサーバーID
（参考情報） 		judge2 / judge1
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 * 4
other AC * 40
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 <utility>
#include <string>
#include <vector>
#include <set>
#include <stack>
#include <queue>
#include <map>
#include <math.h>
#include <string.h>
#include <iomanip>
#include <numeric>
#include <cstdlib>
#include <cstdint>
#include <cmath>
#include <functional>
#include <limits>
#include <cassert>
#include <bitset>
#include <chrono>
#include <random>
#include <memory>
#include <atcoder/all>
/* macro */
 
#define rep(i, a, n) for (int i = (int)(a); i < (int)(n); i++)
#define rrep(i, a, n) for (int i = ((int)(n-1)); i >= (int)(a); i--)
#define Rep(i, a, n) for (i64 i = (i64)(a); i< (i64)(n); i++)
#define RRep(i, a, n) for (i64 i = ((i64)(n-i64(1))); i>=(i64)(a); i--)
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
/* macro end */
/* template */
namespace ebi {
#ifdef LOCAL
#define debug(...)                                                    \
    std::cerr << "LINE: " << __LINE__ << "  [" << #__VA_ARGS__ << "]:", \
        debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif
 
void debug_out() { std::cerr << std::endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head h, Tail... t) {
    std::cerr << " " << h;
    if (sizeof...(t) > 0) std::cout << " :";
    debug_out(t...);
}
 
template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, std::pair<T1, T2> pa) {
    return os << pa.first << " " << pa.second;
}
 
template <typename T>
std::ostream& operator<<(std::ostream& os, std::vector<T> vec) {
    for (std::size_t i = 0; i < vec.size(); i++) os << vec[i] << (i + 1 == vec.size() ? "" : " ");
    return os;
}
std::ostream& operator<<(std::ostream& os, atcoder::modint1000000007 a){
    return os << a.val();
}
std::ostream& operator<<(std::ostream& os, atcoder::modint998244353 a){
    return os << a.val();
}
using size_t = std::size_t;
using i64 = long long;
using u64 = unsigned long long;
template<class T> void fill(std::vector<T> &v) { for(T &e: v) std::cin >> e; }
template<class T>
struct Edge {
    int to;
    T cost;
    Edge(int to, T cost) : to(to), cost(cost) { }
};
template<class T>
using Graph = std::vector<std::vector<Edge<T>>>;
using graph = std::vector<std::vector<int>>;
template <class T>
inline bool chmin(T &a, T b) {
    if (a > b){
        a = b;
        return true;
    }
    return false;
}
 
template <class T>
inline bool chmax(T &a, T b) {
    if (a < b){
        a = b;
        return true;
    }
    return false;
}
template <class T>
T gcd(T a, T b){
    if( b==0 ) return a;
    else return gcd(b, a%b);
}
template <class T>
T lcm(T a, T b) {
    return (a*b)/gcd(a,b);
}
template<class T>
T pow(T x, i64 n) {
    T res = 1;
    while(n>0){
        if(n&1) res = res *x;
        x = x*x;
        n>>=1;
    }
    return res;
}
template<class T>
T mod_pow(T x, i64 n, i64 mod) {
    T res = 1;
    while(n > 0) {
        if(n & 1) res = (res * x)%mod;
        x = (x*x)%mod;
        n >>= 1;
    }
    return res;
}
template<class T>
T scan() {
    T val;
    std::cin >> val;
    return val;
}
 
constexpr i64 LNF = std::numeric_limits<i64>::max()/4;
constexpr int INF = std::numeric_limits<int>::max()/4;
const long double PI = acos(-1);
const std::vector<int> dy = {1,0,-1,0,1,1,-1,-1};
const std::vector<int> dx = {0,1,0,-1,1,-1,1,-1};
}
/* template end */
namespace ebi {
using ld = long double;
using mint = atcoder::modint998244353;
void main_() {
    constexpr int sz = 26;
    int n;
    std::string s;
    std::cin >> n >> s;
    std::vector dp(sz, std::vector<mint>(sz, 0));
    if(n == 1) {
        if(s[0] == '?') {
            std::cout << sz << std::endl;
            return;
        }
        else {
            std::cout << 1 << std::endl;
            return;
        }
    }
    if(s[0] == '?' && s[1] != '?') {
        rep(i,0,sz) {
            if(i == (s[1]-'a')) continue;
            dp[i][s[1]-'a']++;
        }
    }
    else if(s[0] != '?' && s[1] == '?') {
        rep(j,0,sz) {
            if(s[0]-'a' == j) continue;
            dp[s[0]-'a'][j]++;
        }
    }
    else if(s[0] == '?' && s[1] == '?') {
        rep(i,0,sz) {
            rep(j,0,sz) {
                dp[i][j]++;
            }
        }
    }
    else {
        if(s[0] == s[1]) {
            std::cout << 0 << std::endl;
            return;
        }
        dp[s[0]-'a'][s[1]-'a']++;
    }
    rep(p,2,n) {
        std::vector nxt(sz, std::vector<mint>(sz, 0));
        if(s[p] != '?') {
            rep(i,0,sz) {
                rep(j,0,sz) {
                    if(i == j || i == (s[p]-'a') || j == (s[p]-'a')) continue;
                    nxt[j][s[p]-'a'] += dp[i][j];
                }
            }
            dp = nxt;
            continue;
        }
        std::vector<mint> sum(sz, 0);
        rep(j,0,sz) {
            rep(k,0,sz) {
                if(k == j) continue;
                sum[j] += dp[k][j];
            }
        }
        rep(j,0,sz) {
            rep(k,0,sz) {
                nxt[j][k] = sum[j]-dp[k][j];
            }
        }
        dp = nxt;
    }
    mint ans = 0;
    rep(i,0,sz) {
        rep(j,0,sz) {
            if(i == j) continue;
            ans += dp[i][j];
        }
    }
    std::cout << ans.val() << std::endl;
}
}
int main() {
    std::cout << std::fixed << std::setprecision(15);
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    int t = 1;
    while(t--) {
        ebi::main_();
    }
    return 0;
}
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