結果

問題 No.2858 Make a Palindrome
ユーザー kwm_t
提出日時 2024-08-25 15:21:15
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 687 ms / 3,000 ms
コード長 3,095 bytes
コンパイル時間 5,569 ms
コンパイル使用メモリ 313,568 KB
実行使用メモリ 6,948 KB
最終ジャッジ日時 2024-08-25 15:21:39
合計ジャッジ時間 24,232 ms
ジャッジサーバーID
(参考情報)
judge1 / judge5
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
other AC * 40
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ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
using mint = modint998244353;
const int mod = 998244353;
//const int INF = 1e9;
const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t; cin >> t;
const int base = 100;
vector<mint>pow(200005);
pow[0] = 1;
rep2(i, 1, pow.size())pow[i] = pow[i - 1] * base;
while (t--) {
int n, m; cin >> n >> m;
string s; cin >> s;
auto t = s;
reverse(all(t));
long long ans = LINF;
vector<mint>hs(s.size() + 1), ht(t.size() + 1);
rep(i, n) {
hs[i + 1] = hs[i] + pow[i] * (s[i] - 'a' + 1);
ht[i + 1] = ht[i] + pow[i] * (t[i] - 'a' + 1);
}
//rep(i, n + 1) {
// cout << i << " " << hs[i].val() << endl;
//}
// idxx
auto calcHash = [&](int idx, int sz, int type)->mint {
int h = min(sz, n - idx);
int b = ((sz - h) / n) * n;
int t = sz - h - b;
//cout << idx << " " << sz << endl;
//cout << h << " " << b << " " << t << endl;
mint hash = 0;
if (h) {
mint sub = 0;
if (0 == type)sub = (hs[idx + h] - hs[idx]) / pow[idx];
else sub = (ht[idx + h] - ht[idx]) / pow[idx];
hash += sub;
//cout << sub.val() << endl;
}
if (b) {
mint sub = 0;
if (0 == type) sub = hs[n] * (pow[n].pow(b / n) - 1) / (pow[n] - 1) * pow[h];
else sub = ht[n] * (pow[n].pow(b / n) - 1) / (pow[n] - 1) * pow[h];
hash += sub;
}
if (t) {
mint sub = 0;
if (0 == type) sub = pow_mod(base, h + b, mod)*hs[t];
else sub = pow_mod(base, h + b, mod)*ht[t];
hash += sub;
}
return hash;
};
rep(i, n) {
int sz = (m) / 2;
int iR = (i + 1) % n;
mint hR = calcHash(iR, sz, 0);
int iL = (i - 1 + n) % n;
iL = n - 1 - iL;
mint hL = calcHash(iL, sz, 1);
if (hR != hL)continue;
int tmp = 1;
int l = sz - i;
if (l > 0)tmp += (l + n - 1) / n;
int r = sz - (n - 1 - i);//???
if (r > 0)tmp += (r + n - 1) / n;
chmin(ans, tmp);
}
rep(i, n) {
int sz = (m + 1) / 2;
int iR = (i + 0) % n;
mint hR = calcHash(iR, sz, 0);
int iL = (i - 1 + n) % n;
iL = n - 1 - iL;
mint hL = calcHash(iL, sz, 1);
if (hR != hL)continue;
int tmp = 0 != i;
int l = sz - i;
int r = 0 == i ? sz : sz - (n - i);
//cout << l << " " << r << endl;
if (l > 0)tmp += (l + n - 1) / n;
if (r > 0)tmp += (r + n - 1) / n;
//cout << i << endl;
chmin(ans, tmp);
}
if (LINF == ans)ans = -1;
cout << ans << endl;
}
return 0;
}
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