/*
PROG: source
LANG: C++11
_____
.' '.
/ 0 0 \
| ^ |
| \ / |
\ '---' /
'._____.'
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
struct chash
{
int operator()(int x) const
{
x ^= (x >> 20) ^ (x >> 12);
return x ^ (x >> 7) ^ (x >> 4);
}
int operator()(long long x) const
{
return x ^ (x >> 32);
}
};
template<typename T> using orderedset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using hashtable = gp_hash_table<T, U, chash>;
template<class T>
void readi(T &x)
{
T input = 0;
bool negative = false;
char c = ' ';
while (c < '-')
{
c = getchar();
}
if (c == '-')
{
negative = true;
c = getchar();
}
while (c >= '0')
{
input = input * 10 + (c - '0');
c = getchar();
}
if (negative)
{
input = -input;
}
x = input;
}
template<class T>
void printi(T output)
{
if (output == 0)
{
putchar('0');
return;
}
if (output < 0)
{
putchar('-');
output = -output;
}
int aout[20];
int ilen = 0;
while(output)
{
aout[ilen] = ((output % 10));
output /= 10;
ilen++;
}
for (int i = ilen - 1; i >= 0; i--)
{
putchar(aout[i] + '0');
}
return;
}
template<class T>
void ckmin(T &a, T b)
{
a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
a = max(a, b);
}
template<class T, class U>
T normalize(T x, U mod = 1000000007)
{
return (((x % mod) + mod) % mod);
}
long long randomizell(long long mod)
{
return ((1ll << 45) * rand() + (1ll << 30) * rand() + (1ll << 15) * rand() + rand()) % mod;
}
int randomize(int mod)
{
return ((1ll << 15) * rand() + rand()) % mod;
}
#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define debug(x) cerr << #x << " = " << x << endl;
const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-10;
#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 300013
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;
int N;
int s[MAXN], t[2 * MAXN];
int len[2 * MAXN];
vector<int> sse[MAXN], sfi[MAXN];
int suf[MAXN], srank[MAXN], lcp[MAXN];
int sparse[25][MAXN];
int sval[25][MAXN];
ll ans = 0;
void manacher()
{
int lt = 0, rt = 0;
for (int i = 0; i <= 2 * N; i++)
{
len[i] = min(rt - i, len[lt + (rt - i)]);
while(0 <= i - len[i] && i + len[i] <= 2 * N && t[i - len[i]] == t[i + len[i]])
{
len[i]++;
}
if (i + len[i] > rt)
{
lt = i - len[i];
rt = i + len[i];
}
len[i]--;
}
return;
}
void buildsuf()
{
for (int i = 0; i < N; i++)
{
sval[0][i] = s[i];
}
for (int i = 0; i < 20; i++)
{
int Z = max(30, N);
for (int j = 0; j <= Z; j++)
{
sse[j].clear();
sfi[j].clear();
}
for (int j = 0; j < N; j++)
{
int val1 = (((j + (1 << i)) >= N) ? 0 : sval[i][j + (1 << i)]);
sse[val1].PB(j);
}
for (int j = 0; j <= Z; j++)
{
for (int idx : sse[j])
{
int val = sval[i][idx];
sfi[val].PB(idx);
}
}
pii was = {-1, -1}; int K = 0;
for (int j = 0; j <= Z; j++)
{
for (int idx : sfi[j])
{
pii cur = {sval[i][idx], ((idx + (1 << i)) >= N ? 0 : sval[i][idx + (1 << i)])};
if (cur > was)
{
K++;
was = cur;
}
sval[i + 1][idx] = K;
}
}
}
for (int i = 0; i < N; i++)
{
srank[i] = sval[20][i] - 1;
suf[srank[i]] = i;
}
int best = 0;
for (int i = 0; i < N; i++)
{
int idx = srank[i];
if (idx == N - 1)
{
lcp[idx] = 0;
continue;
}
int j = suf[idx + 1];
while(i + best < N && j + best < N && s[i + best] == s[j + best]) best++;
lcp[idx] = best;
if (best) best--;
}
}
int query(int lt, int rt)
{
int lg = 31 - __builtin_clz(rt - lt + 1);
int res = min(sparse[lg][lt], sparse[lg][rt - (1 << lg) + 1]);
return res;
// cerr << "res = " << res << endl;
// for (int j = lt; j <= rt; j++)
// {
// cerr << lcp[j] << ' ';
// }
// cerr << endl;
}
int chk(int lt, int rt)
{
int sz = rt - lt + 1, res = 1, cur = srank[lt], lo, hi;
// cerr << "count " << lt << ' ' << rt << endl;
lo = 0, hi = cur;
while(hi > lo)
{
int mid = (hi + lo) / 2;
if (query(mid, cur - 1) < sz)
{
lo = mid + 1;
}
else
{
hi = mid;
}
}
res += (cur - lo);
lo = cur - 1, hi = N - 2;
while(hi > lo)
{
int mid = (hi + lo + 1) / 2;
if (query(cur, mid) < sz)
{
hi = mid - 1;
}
else
{
lo = mid;
}
}
res += (lo - cur + 1);
// cerr << "res " << res << endl;
return res;
}
int32_t main()
{
ios_base::sync_with_stdio(0);
srand(time(0));
// cout << fixed << setprecision(10);
// cerr << fixed << setprecision(10);
if (fopen("input.in", "r"))
{
freopen ("input.in", "r", stdin);
freopen ("output.out", "w", stdout);
}
string temps; cin >> temps;
N = temps.length();
for (int i = 0; i < N; i++)
{
s[i] = temps[i] - 'a' + 1;
}
for (int i = 0; i < N; i++)
{
t[2 * i + 1] = s[i];
}
manacher();
// for (int i = 0; i <= 2 * N; i++)
// {
// cerr << t[i] << ' ';
// }
// cerr << endl;
// for (int i = 0; i <= 2 * N; i++)
// {
// cerr << len[i] << ' ';
// }
// cerr << endl;
buildsuf();
for (int i = 0; i < N - 1; i++)
{
sparse[0][i] = lcp[i];
}
for (int i = 1; i < 20; i++)
{
for (int j = 0; j < N - 1; j++)
{
sparse[i][j] = min(sparse[i - 1][j], ((j + (1 << (i - 1)) < N - 1) ? sparse[i - 1][j + (1 << (i - 1))] : 0));
}
}
// for (int i = 0; i < N; i++)
// {
// cerr << suf[i] << endl;
// }
for (int i = 1; i < 2 * N; i++)
{
int lt, rt;
if (i % 2)
{
lt = (i / 2) - (len[i] / 2);
rt = (i / 2) + (len[i] / 2);
}
else
{
lt = (i / 2) - (len[i] / 2);
rt = (i / 2) + (len[i] / 2) - 1;
}
if (lt > rt)
{
continue;
}
while(lt <= rt)
{
ckmax(ans, 1ll * (rt - lt + 1) * chk(lt, rt));
lt++; rt--;
}
// cerr << lt << ' ' << rt << endl;
}
// for (int i = 0; i <= 2 * N; i++)
// {
// cerr << len[i] << ' ';
// }
// cerr << endl;
cout << ans << '\n';
// cerr << "time elapsed = " << (clock() / (CLOCKS_PER_SEC / 1000)) << " ms" << endl;
return 0;
}
Compilation message
palindrome.cpp: In function 'int32_t main()':
palindrome.cpp:289:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen ("input.in", "r", stdin);
~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
palindrome.cpp:290:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen ("output.out", "w", stdout);
~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
15 ms |
14712 KB |
Output is correct |
| 2 |
Correct |
17 ms |
14832 KB |
Output is correct |
| 3 |
Correct |
15 ms |
14936 KB |
Output is correct |
| 4 |
Correct |
18 ms |
14936 KB |
Output is correct |
| 5 |
Correct |
19 ms |
14936 KB |
Output is correct |
| 6 |
Correct |
15 ms |
14936 KB |
Output is correct |
| 7 |
Correct |
17 ms |
14968 KB |
Output is correct |
| 8 |
Correct |
16 ms |
14972 KB |
Output is correct |
| 9 |
Correct |
18 ms |
14976 KB |
Output is correct |
| 10 |
Correct |
20 ms |
14980 KB |
Output is correct |
| 11 |
Correct |
16 ms |
14988 KB |
Output is correct |
| 12 |
Correct |
19 ms |
15044 KB |
Output is correct |
| 13 |
Correct |
15 ms |
15076 KB |
Output is correct |
| 14 |
Correct |
19 ms |
15076 KB |
Output is correct |
| 15 |
Correct |
17 ms |
15076 KB |
Output is correct |
| 16 |
Correct |
21 ms |
15076 KB |
Output is correct |
| 17 |
Correct |
17 ms |
15116 KB |
Output is correct |
| 18 |
Correct |
18 ms |
15120 KB |
Output is correct |
| 19 |
Correct |
19 ms |
15124 KB |
Output is correct |
| 20 |
Correct |
21 ms |
15128 KB |
Output is correct |
| 21 |
Correct |
19 ms |
15208 KB |
Output is correct |
| 22 |
Correct |
16 ms |
15208 KB |
Output is correct |
| 23 |
Correct |
18 ms |
15208 KB |
Output is correct |
| 24 |
Correct |
17 ms |
15208 KB |
Output is correct |
| 25 |
Correct |
20 ms |
15208 KB |
Output is correct |
| 26 |
Correct |
18 ms |
15208 KB |
Output is correct |
| 27 |
Correct |
19 ms |
15208 KB |
Output is correct |
| 28 |
Correct |
15 ms |
15208 KB |
Output is correct |
| 29 |
Correct |
15 ms |
15208 KB |
Output is correct |
| 30 |
Correct |
16 ms |
15208 KB |
Output is correct |
| 31 |
Correct |
15 ms |
15208 KB |
Output is correct |
| 32 |
Correct |
21 ms |
15208 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
71 ms |
15456 KB |
Output is correct |
| 2 |
Correct |
42 ms |
15588 KB |
Output is correct |
| 3 |
Correct |
106 ms |
15696 KB |
Output is correct |
| 4 |
Correct |
20 ms |
15696 KB |
Output is correct |
| 5 |
Correct |
92 ms |
15696 KB |
Output is correct |
| 6 |
Correct |
88 ms |
15696 KB |
Output is correct |
| 7 |
Correct |
17 ms |
15696 KB |
Output is correct |
| 8 |
Correct |
57 ms |
15696 KB |
Output is correct |
| 9 |
Correct |
24 ms |
15696 KB |
Output is correct |
| 10 |
Correct |
20 ms |
15696 KB |
Output is correct |
| 11 |
Correct |
19 ms |
15696 KB |
Output is correct |
| 12 |
Correct |
25 ms |
15696 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1077 ms |
18832 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1037 ms |
51244 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1059 ms |
109556 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
