#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,tune=native")
#include <bits/stdc++.h>
using namespace std;
vector<int> suffix_array(string S) {
S += "$";
int N = (int)S.size();
vector<int> ord(N), comp(N);
for (int i = 0; i < N; i++) {
ord[i] = i;
comp[i] = S[i];
}
sort(ord.begin(), ord.end(), [&](int i, int j) { return S[i] < S[j]; });
vector<int> tmp(N), cnt(N + 1);
auto Update = [&](int d) {
int ptr = 0, x = -1, y = -1;
for (int i : ord) {
int j = i + d < N ? i + d : i + d - N;
tmp[i] = comp[i] != x || comp[j] != y ? ++ptr : ptr;
x = comp[i], y = comp[j];
}
comp = tmp;
};
auto Sort = [&](int d) {
cnt.assign(N + 1, 0);
for (int value : comp) {
cnt[value]++;
}
partial_sum(cnt.begin(), cnt.end(), cnt.begin());
for (int i : ord) {
int j = i + d < N ? i + d : i + d - N;
tmp[cnt[comp[j] - 1]++] = i;
}
ord = tmp;
};
Update(0);
for (int d = 1; d < N; d++) {
Sort(d);
Sort(0);
Update(d);
}
return ord;
}
vector<int> find_lcp(string S, vector<int> ord) {
S += "$";
int N = (int)S.size();
vector<int> pos(N);
for (int i = 0; i < N; i++) {
pos[ord[i]] = i;
}
vector<int> lcp(N);
int l = 0;
for (int i = 0; i < N; i++) {
if (pos[i] == N - 1) {
continue;
}
int j = ord[pos[i] + 1];
while (max(i, j) + l < N && S[i + l] == S[j + l]) {
l++;
}
lcp[pos[i]] = l;
l = max(0, l - 1);
}
return lcp;
}
vector<int> manacher_odd(string S) {
S += "$";
int N = (int)S.size();
vector<int> x(N, 1);
int l = 0, r = 0;
for (int i = 1; i < N; i++) {
if (i < r) {
x[i] = min(r - i + 1, x[l + r - i]);
}
while (i - x[i] >= 0 && i + x[i] < N && S[i - x[i]] == S[i + x[i]]) {
x[i]++;
}
if (i + x[i] - 1 > r) {
l = i - x[i] + 1;
r = i + x[i] - 1;
}
}
x.pop_back();
return x;
}
vector<int> manacher_even(string s) {
int n = (int)s.size();
vector<int> d(n, 0);
int l = -1, r = -1;
for (int i = 0; i < n - 1; i++) {
if (i < r) {
d[i] = min(r - i, d[l + r - i - 1]);
}
while (i - d[i] >= 0 && i + d[i] + 1 < n && s[i - d[i]] == s[i + d[i] + 1]) {
d[i]++;
}
if (i + d[i] > r) {
l = i - d[i] + 1, r = i + d[i];
}
}
rotate(d.rbegin(), d.rbegin() + 1, d.rend());
return d;
}
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
string S;
cin >> S;
int N = (int)S.size();
vector<int> ord = suffix_array(S);
vector<int> lcp = find_lcp(S, ord);
vector<int> x_odd = manacher_odd(S), x_even = manacher_even(S);
vector<int> pos(N + 1);
for (int i = 0; i <= N; i++) {
pos[ord[i]] = i;
}
vector<int> max_pal(N + 1);
set<int> odd, even;
vector<vector<int>> del_odd(N), del_even(N);
for (int i = N - 1; i >= 0; i--) {
odd.insert(i);
even.insert(i);
del_odd[i - x_odd[i] + 1].push_back(i);
del_even[i - x_even[i]].push_back(i);
max_pal[pos[i]] = max((*odd.rbegin() - i) * 2 + 1, (*even.rbegin() - i) * 2);
for (int v : del_odd[i]) {
odd.erase(v);
}
for (int v : del_even[i]) {
even.erase(v);
}
}
vector<int> A;
for (int i = 0; i <= N; i++) {
A.push_back(max_pal[i]);
A.push_back(lcp[i]);
}
long long ans = 1;
vector<int> L(2 * (N + 1)), R(2 * (N + 1));
stack<int> st;
for (int i = 0; i < 2 * (N + 1); i++) {
while (!st.empty() && A[i] <= A[st.top()]) {
st.pop();
}
L[i] = st.empty() ? -1 : st.top();
st.push(i);
}
st = stack<int>();
for (int i = 2 * (N + 1) - 1; i >= 0; i--) {
while (!st.empty() && A[i] <= A[st.top()]) {
st.pop();
}
R[i] = st.empty() ? 2 * (N + 1) : st.top();
if (i % 2 == 0) {
ans = max(ans, 1LL * ((R[i] - L[i] + 1) / 2) * A[i]);
}
st.push(i);
}
cout << ans << "\n";
}
Compilation message
In file included from /usr/include/x86_64-linux-gnu/c++/10/bits/gthr.h:148,
from /usr/include/c++/10/ext/atomicity.h:35,
from /usr/include/c++/10/bits/ios_base.h:39,
from /usr/include/c++/10/ios:42,
from /usr/include/c++/10/istream:38,
from /usr/include/c++/10/sstream:38,
from /usr/include/c++/10/complex:45,
from /usr/include/c++/10/ccomplex:39,
from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:54,
from palindrome.cpp:3:
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:102:1: error: attribute value 'tune=native' was already specified in 'target' attribute
102 | __gthrw(pthread_once)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:102:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:103:1: error: attribute value 'tune=native' was already specified in 'target' attribute
103 | __gthrw(pthread_getspecific)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:103:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:104:1: error: attribute value 'tune=native' was already specified in 'target' attribute
104 | __gthrw(pthread_setspecific)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:104:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:106:1: error: attribute value 'tune=native' was already specified in 'target' attribute
106 | __gthrw(pthread_create)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:106:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:107:1: error: attribute value 'tune=native' was already specified in 'target' attribute
107 | __gthrw(pthread_join)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:107:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:108:1: error: attribute value 'tune=native' was already specified in 'target' attribute
108 | __gthrw(pthread_equal)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:108:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:109:1: error: attribute value 'tune=native' was already specified in 'target' attribute
109 | __gthrw(pthread_self)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:109:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:110:1: error: attribute value 'tune=native' was already specified in 'target' attribute
110 | __gthrw(pthread_detach)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:110:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:112:1: error: attribute value 'tune=native' was already specified in 'target' attribute
112 | __gthrw(pthread_cancel)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:112:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:114:1: error: attribute value 'tune=native' was already specified in 'target' attribute
114 | __gthrw(sched_yield)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:114:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:116:1: error: attribute value 'tune=native' was already specified in 'target' attribute
116 | __gthrw(pthread_mutex_lock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:116:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:117:1: error: attribute value 'tune=native' was already specified in 'target' attribute
117 | __gthrw(pthread_mutex_trylock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:117:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:119:1: error: attribute value 'tune=native' was already specified in 'target' attribute
119 | __gthrw(pthread_mutex_timedlock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:119:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:121:1: error: attribute value 'tune=native' was already specified in 'target' attribute
121 | __gthrw(pthread_mutex_unlock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:121:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:122:1: error: attribute value 'tune=native' was already specified in 'target' attribute
122 | __gthrw(pthread_mutex_init)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:122:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:123:1: error: attribute value 'tune=native' was already specified in 'target' attribute
123 | __gthrw(pthread_mutex_destroy)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:123:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:125:1: error: attribute value 'tune=native' was already specified in 'target' attribute
125 | __gthrw(pthread_cond_init)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:125:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:126:1: error: attribute value 'tune=native' was already specified in 'target' attribute
126 | __gthrw(pthread_cond_broadcast)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:126:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:127:1: error: attribute value 'tune=native' was already specified in 'target' attribute
127 | __gthrw(pthread_cond_signal)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:127:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:128:1: error: attribute value 'tune=native' was already specified in 'target' attribute
128 | __gthrw(pthread_cond_wait)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:128:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:129:1: error: attribute value 'tune=native' was already specified in 'target' attribute
129 | __gthrw(pthread_cond_timedwait)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:129:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:130:1: error: attribute value 'tune=native' was already specified in 'target' attribute
130 | __gthrw(pthread_cond_destroy)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:130:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:132:1: error: attribute value 'tune=native' was already specified in 'target' attribute
132 | __gthrw(pthread_key_create)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:132:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:133:1: error: attribute value 'tune=native' was already specified in 'target' attribute
133 | __gthrw(pthread_key_delete)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:133:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:134:1: error: attribute value 'tune=native' was already specified in 'target' attribute
134 | __gthrw(pthread_mutexattr_init)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:134:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:135:1: error: attribute value 'tune=native' was already specified in 'target' attribute
135 | __gthrw(pthread_mutexattr_settype)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:135:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:136:1: error: attribute value 'tune=native' was already specified in 'target' attribute
136 | __gthrw(pthread_mutexattr_destroy)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:136:1: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:237:10: error: attribute value 'tune=native' was already specified in 'target' attribute
237 | __gthrw2(__gthrw_(__pthread_key_create),
| ^~~~~~~~
/usr/include/x86_64-linux-gnu/c++/10/bits/gthr-default.h:237:10: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:73:3: error: attribute value 'tune=native' was already specified in 'target' attribute
73 | _GLIBCXX_GTHRW(rwlock_rdlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/10/shared_mutex:73:3: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:74:3: error: attribute value 'tune=native' was already specified in 'target' attribute
74 | _GLIBCXX_GTHRW(rwlock_tryrdlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/10/shared_mutex:74:3: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:75:3: error: attribute value 'tune=native' was already specified in 'target' attribute
75 | _GLIBCXX_GTHRW(rwlock_wrlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/10/shared_mutex:75:3: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:76:3: error: attribute value 'tune=native' was already specified in 'target' attribute
76 | _GLIBCXX_GTHRW(rwlock_trywrlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/10/shared_mutex:76:3: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:77:3: error: attribute value 'tune=native' was already specified in 'target' attribute
77 | _GLIBCXX_GTHRW(rwlock_unlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/10/shared_mutex:77:3: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:91:4: error: attribute value 'tune=native' was already specified in 'target' attribute
91 | __gthrw(pthread_rwlock_timedrdlock);
| ^~~~~~~
/usr/include/c++/10/shared_mutex:91:4: error: attribute value 'tune=native' was already specified in 'target' attribute
/usr/include/c++/10/shared_mutex:101:4: error: attribute value 'tune=native' was already specified in 'target' attribute
101 | __gthrw(pthread_rwlock_timedwrlock);
| ^~~~~~~
/usr/include/c++/10/shared_mutex:101:4: error: attribute value 'tune=native' was already specified in 'target' attribute
