// Author : Hoang Van Tra - HSGS Bac Giang
// Train VOI 2023 - 2024
#include <bits/stdc++.h>
using namespace std;
// -------------------------------------------------------INDEF-----------------------------------------------------------------------
#define For(i,a,b) for(int i = a; i <= b; i++)
#define Ford(i,a,b) for(int i = a; i >= b; i--)
#define ll long long
#define ii pair<int,int>
#define fi first
#define se second
#define all(v) v.begin(),v.end()
#define RRH(v) v.resize(unique(all(v)) - v.begin())
const int N = 1e6+7;
const int M = 1e9+7;
const ll oo = 1e18;
const int block = 708;
namespace IO
{
#define getchar() (ipos==iend and (iend=(ipos=_ibuf)+fread(_ibuf,1,__bufsize,stdin),ipos==iend)?EOF:*ipos++)
#define putchar(ch) (opos==oend?fwrite(_obuf,1,__bufsize,stdout),opos=_obuf:0,*opos++=(ch))
#define __bufsize (1<<20)
char _ibuf[__bufsize],_obuf[__bufsize],_stk[20];
char *ipos=_ibuf,*iend=_ibuf,*opos=_obuf,*oend = _obuf+__bufsize,*stkpos = _stk;
struct END{~END(){fwrite(_obuf,1,opos-_obuf,stdout);}}__;
inline void read(int&x)
{
register int f=0,ch;
for(;!isdigit(ch);ch=getchar())if(ch=='-')f=1;
for(x=0;isdigit(ch);ch=getchar())x=(x<<3ll)+(x<<1ll)+(ch^48);
x=f?-x:x;
}
inline void readll(ll&x)
{
register ll f=0,ch;
for(;!isdigit(ch);ch=getchar())if(ch=='-')f=1;
for(x=0;isdigit(ch);ch=getchar())x=(x<<3ll)+(x<<1ll)+(ch^48);
x=f?-x:x;
}
inline void write(ll x)
{
if(x<0)putchar('-'),x=-x;
while(*++stkpos=x%10^48,x/=10,x);
while(stkpos!=_stk)putchar(*stkpos--);
}
};
using namespace IO;
string s;
namespace sub2 {
const ll base1 = 31;
const ll base2 = 33;
const ll mod1 = 1e9 + 7;
const ll mod2 = 2000037241ll;
int n;
ll p[5009], h[5009], ha[5009];
int cnt[N];
ll ans = 0;
ll pre(int l, int r) {
return (h[r] - h[l - 1] * p[r - l + 1] + 1ll * mod1 * mod1) % mod1;
}
ll suf(int l, int r) {
return (ha[r] - ha[l - 1] * p[r - l + 1] + 1ll * mod1 * mod1) % mod1;
}
bool check(int l, int r) {
if(pre(l, r) == suf(n - r + 1, n - l + 1)) return 1;
return 0;
}
ll po[5009], hasa[5009], has[5009];
ll get_pre(int l, int r) {
return (hasa[r] - hasa[l - 1] * po[r - l + 1] + 1ll * mod2 * mod2) % mod2;
}
ll get_suf(int l, int r) {
return (has[r] - has[l - 1] * po[r - l + 1] + 1ll * mod2 * mod2) % mod2;
}
bool check2(int l, int r) {
if(get_pre(l, r) == get_suf(n - r + 1, n - l + 1)) return 1;
return 0;
}
void solve() {
n = s.size();
s = ' ' + s;
po[0] = p[0] = 1;
h[0] = hasa[0] = ha[0] = has[0] = 0;
// h , ha la mod1
// hasa, has la mod2
For(i,1,n) {
p[i] = p[i - 1] * base1 * 1ll;
po[i] = po[i - 1] * base2 * 1ll;
p[i] %= mod1;
po[i] %= mod2;
h[i] = (h[i - 1] * base1 + s[i] - 'a' + 1) % mod1;
hasa[i] = (hasa[i - 1] * base2 + s[i] - 'a' + 1) % mod2;
ha[i] = (ha[i - 1] * base1 * 1ll + s[n - i + 1] - 'a' + 1) % mod1;
has[i] = (has[i - 1] * base2 * 1ll + s[n - i + 1] - 'a' + 1) % mod2;
}
For(i,1,n) {
For(j,i,n) {
if(i == j) {
ans++;
cnt[i]++;
}
else {
if(check(i, j) && check2(i, j)) {
cnt[i]++;
cnt[j]++;
ans++;
}
}
}
}
For(i,1,n) {
for(char c = 'a'; c <= 'z'; c++) {
ll tmp = ans - cnt[i];
For(j,1,n) {
if(i == j) tmp++;
else {
if(i > j) {
int l = j;
int r = i;
ll hashing = ((c - 'a' + 1) * 1ll * p[r - l] % mod1 + pre(l, r - 1)) % mod1;
ll hashingg = (suf(l + 1, r) * base1 + (c - 'a' + 1) * 1ll % mod1) % mod1;
if(hashingg != hashing) continue;
else {
hashing = ((c - 'a' + 1) * 1ll * po[r - l] % mod2 + get_pre(l, r - 1)) % mod2;
hashingg = (get_suf(l + 1, r) * base2 + (c - 'a' + 1) * 1ll % mod2) % mod2;
if(hashingg == hashing) tmp++;
}
}
else {
int l = i;
int r = j;
ll hashing = ((c - 'a' + 1) * 1ll + pre(l + 1, r) * base1 % mod1) % mod1;
ll hashingg = ((c - 'a' + 1) * 1ll * p[r - l] % mod1 + suf(l, r - 1) * base1 % mod1) % mod1;
if(hashingg != hashing) continue;
else {
hashing = ((c - 'a' + 1) * 1ll + get_pre(l + 1, r) * base2 % mod2) % mod2;
hashingg = ((c - 'a' + 1) * 1ll * po[r - l] % mod2 + get_suf(l, r - 1) * base2 % mod2) % mod2;
if(hashingg == hashing) tmp++;
}
}
}
}
ans = max(ans, tmp);
}
}
cout << ans;
}
}
// -------------------------------------------------------ENDEF----------------------------------------------------------------------
int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
#define TASK ""
if(fopen(TASK".inp", "r")) {
freopen(TASK".inp", "r", stdin);
freopen(TASK".out", "w", stdout);
}
cin >> s;
int n = s.size();
if(n <= 5000) {
sub2 :: solve();
}
// else {
// subac :: solve();
// }
return 0;
}
Compilation message
palinilap.cpp: In function 'int32_t main()':
palinilap.cpp:182:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
182 | freopen(TASK".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
palinilap.cpp:183:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
183 | freopen(TASK".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
2392 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1054 ms |
2652 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
2648 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
