#718492 (C++23) No.1755 Almost Palindrome

• 問題: No.1755 Almost Palindrome
• ユーザー: beet
• 提出日時: 2021-11-20 14:12:39
• 言語: C++23 (gcc 15.2.0 + boost 1.89.0)
• 結果: CE (最新)
  AC
  (最初)
• 実行時間: -
• コード長: 3,266 bytes
• コンパイル時間: 37 ms
• 最終ジャッジ日時: 2026-03-04 21:43:47
• 合計ジャッジ時間: 373 ms
• ジャッジサーバーID （参考情報）: judge1 / judge3

コンパイルメッセージ

eb047ab9497a
[/j_bin/judge_tool judge 40000 ../CompileMemory.txt /dev/null sud /dev/null _ g++-15 -O2 -lm -std=c++23 -Wuninitialized -DONLINE_JUDGE -o a.out main.cpp]
strconv.Atoi: parsing "../CompileMemory.txt": invalid syntax
goroutine 1 [running]:
runtime/debug.Stack()
	/home/yuki2006/go/pkg/mod/golang.org/[e-mail]-amd64/src/runtime/debug/stack.go:26 +0x5e
main.main.func1()
	/home/yuki2006/gopath/src/yukicoder/judge/main.go:22 +0x57
panic({0x7d6880?, 0xc0000f6240?})
	/home/yuki2006/go/pkg/mod/golang.org/[e-mail]-amd64/src/runtime/panic.go:783 +0x132
main.judgeMain({0xc000012150, 0x5?, 0x0?})
	/home/yuki2006/gopath/src/yukicoder/judge/judge_linux.go:121 +0x4b1
main.main()
	/home/yuki2006/gopath/src/yukicoder/judge/main.go:97 +0x277

ソースコード

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

using Int = long long;
const char newl = '\n';

template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
template<typename T> void drop(const T &x){cout<<x<<endl;exit(0);}
template<typename T=int>
vector<T> read(size_t n){
  vector<T> ts(n);
  for(size_t i=0;i<n;i++) cin>>ts[i];
  return ts;
}

template<typename T, T MOD = 1000000007>
struct Mint{
  inline static constexpr T mod = MOD;
  T v;
  Mint():v(0){}
  Mint(signed v):v(v){}
  Mint(long long t){v=t%MOD;if(v<0) v+=MOD;}

  Mint pow(long long k){
    Mint res(1),tmp(v);
    while(k){
      if(k&1) res*=tmp;
      tmp*=tmp;
      k>>=1;
    }
    return res;
  }

  static Mint add_identity(){return Mint(0);}
  static Mint mul_identity(){return Mint(1);}

  Mint inv(){return pow(MOD-2);}

  Mint& operator+=(Mint a){v+=a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator-=(Mint a){v+=MOD-a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator*=(Mint a){v=1LL*v*a.v%MOD;return *this;}
  Mint& operator/=(Mint a){return (*this)*=a.inv();}

  Mint operator+(Mint a) const{return Mint(v)+=a;}
  Mint operator-(Mint a) const{return Mint(v)-=a;}
  Mint operator*(Mint a) const{return Mint(v)*=a;}
  Mint operator/(Mint a) const{return Mint(v)/=a;}

  Mint operator+() const{return *this;}
  Mint operator-() const{return v?Mint(MOD-v):Mint(v);}

  bool operator==(const Mint a)const{return v==a.v;}
  bool operator!=(const Mint a)const{return v!=a.v;}

  static Mint comb(long long n,int k){
    Mint num(1),dom(1);
    for(int i=0;i<k;i++){
      num*=Mint(n-i);
      dom*=Mint(i+1);
    }
    return num/dom;
  }
};
template<typename T, T MOD>
ostream& operator<<(ostream &os,Mint<T, MOD> m){os<<m.v;return os;}

// [0, n]
template<typename T>
vector<T> powers(int n,T x){
  vector<T> po(n+1,T(1));
  for(int i=0;i<n;i++) po[i+1]=po[i]*x;
  return po;
}

bool is_palindrome(string s){
  return s==string(s.rbegin(),s.rend());
}

bool check(string s){
  if(is_palindrome(s)) return false;
  for(int i=0;i<(int)s.size();i++)
    if(is_palindrome(s.substr(0,i)+s.substr(i+1)))
      return true;
  return false;
}


//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);


  if(0){
    const int MAX = 6;
    for(int n=1;n<=MAX;n++){
      using ll = long long;
      ll sz=pow(26,n);
      string s(n,'a');
      int cnt=0;
      for(ll bit=0;bit<sz;bit++){
        ll tmp=bit;
        for(int i=0;i<n;i++){
          s[i]='a'+(tmp%26);
          tmp/=26;
        }
        if(check(s)) cnt++;//cout<<s<<endl;
      }
      cout<<n<<":"<<cnt<<endl;
    }
    return 0;
  }

  using M = Mint<int, 998244353>;
  auto po=powers<M>(1e6+10,M(26));

  vector<M> dp(1e6+10,0);
  for(int i=4;i<(int)dp.size();i+=2) dp[i]=dp[i-2]+po[(i-4)/2];

  auto solve=[&](){
    int n;
    cin>>n;
    if(n==1){
      cout<<0<<newl;
      return;
    }
    if(n==2){
      cout<<650<<newl;
      return;
    }
    auto calc=[&](int x){return po[(x+1)/2];};
    M ans=calc(n-1)*(M(1)+M(25)*M(n));
    if(~n&1) ans-=M(26*25);
    if(~n&1) ans-=M(26*26*25)*dp[n];
    ans-=calc(n);
    cout<<ans<<newl;
  };

  int T;
  cin>>T;
  while(T--) solve();

  return 0;
}