結果

問題 No.765 ukuku 2
ユーザー rogi52
提出日時 2022-02-22 19:22:29
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 3,600 bytes
コンパイル時間 2,185 ms
コンパイル使用メモリ 201,204 KB
最終ジャッジ日時 2025-01-28 01:26:35
ジャッジサーバーID
(参考情報)
judge5 / judge5
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 * 2
other AC * 40 WA * 8
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 <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;
struct RollingHash {
static constexpr int M = 2;
static constexpr long long MODS[M] = {999999937, 1000000007};
static constexpr long long BASE = 9973;
vector<long long> powb[M], hash[M];
int n;
RollingHash() {}
RollingHash(const string& str) { init(str); }
void init(const string& str) {
n = str.size();
for (int k = 0; k < M; k++) {
powb[k].resize(n + 1, 1);
hash[k].resize(n + 1, 0);
for (int i = 0; i < n; i++) {
hash[k][i + 1] = (hash[k][i] * BASE + str[i]) % MODS[k];
powb[k][i + 1] = powb[k][i] * BASE % MODS[k];
}
}
}
// get hash str[l,r)
long long get(int l, int r, int k) {
long long res = hash[k][r] - hash[k][l] * powb[k][r - l] % MODS[k];
if (res < 0) res += MODS[k];
return res;
}
};
bool match(RollingHash& rh1, int l1, int r1, RollingHash& rh2, int l2, int r2) {
bool res = true;
for (int k = 0; k < RollingHash::M; k++) {
res &= rh1.get(l1, r1, k) == rh2.get(l2, r2, k);
}
return res;
}
int main(){
cin.tie(0);
ios::sync_with_stdio(0);
string S; cin >> S;
int N = S.size();
string T = S;
reverse(T.begin(), T.end());
if(S == T) {
cout << N - 1 << endl;
return 0;
}
RollingHash HS(S), HT(T);
int ans = 0;
rep(i,N) {
int L = 0, R = min(i, N - (i + 1)) + 1;
while(R - L > 1) {
int x = (R + L) / 2;
(match(HS, i + 1, i + 1 + x, HT, N - i, N - i + x) ? L : R) = x;
}
if(L == min(i, N - (i + 1))) {
ans = max(ans, L + 1 + L);
continue;
}
int SL = L, SR = R;
{
L = SL, R = SR;
int pos = L;
R = min(i, N - (i + 2)) + 1;
while(R - L > 1) {
int x = (R + L) / 2;
(match(HS, i + 2 + pos, i + 2 + x, HT, N - i + pos, N - i + x) ? L : R) = x;
}
ans = max(ans, L + 1 + L);
}
{
L = SL, R = SR;
int pos = L;
R = min(i - 1, N - (i + 1)) + 1;
while(R - L > 1) {
int x = (R + L) / 2;
(match(HS, i + pos, i + 1 + x, HT, N - i + pos + 1, N - i + x + 1) ? L : R) = x;
}
ans = max(ans, L + 1 + L);
}
}
rep(i,N-1) if(S[i] == S[i + 1]) {
int L = 0, R = min(i, N - (i + 2)) + 1;
while(R - L > 1) {
int x = (R + L) / 2;
(match(HS, i + 2, i + 2 + x, HT, N - i, N - i + x) ? L : R) = x;
}
if(L == min(i, N - (i + 2))) {
ans = max(ans, L + 2 + L);
continue;
}
int SL = L, SR = R;
{
L = SL, R = SR;
int pos = L;
R = min(i, N - (i + 3)) + 1;
while(R - L > 1) {
int x = (R + L) / 2;
(match(HS, i + 3 + pos, i + 3 + x, HT, N - i + pos, N - i + x) ? L : R) = x;
}
ans = max(ans, L + 2 + L);
}
{
L = SL, R = SR;
int pos = L;
R = min(i - 1, N - (i + 2)) + 1;
while(R - L > 1) {
int x = (R + L) / 2;
(match(HS, i + 2 + pos, i + 2 + x, HT, N - i + pos + 1, N - i + x + 1) ? L : R) = x;
}
ans = max(ans, L + 2 + L);
}
}
cout << ans << endl;
}
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