#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define bit(X,i) ((X>>i)&1)
#define fori(i,d,c) for(int i = d; i <= c; ++ i)
#define ford(i,d,c) for(int i = d; i >= c; -- i)
#define all(V) V.begin(), V.end()
#define RRH(V) V.resize(unique(all(V))-V.begin())
#define Task "palival"
using namespace std;
using ll = long long;
using ld = long double;
const int maxn = 1e5 + 5;
const int maxm = 1e6 + 5;
const int base = 101;
string s, BASE_STRING;
int n;
void read() {
cin >> s;
BASE_STRING = s;
n = s.size();
s = " " + s;
}
namespace sub1{
int f[105][105];
int calc() {
ford(i,n,1) {
fori(j,i,n) {
if (j == i) f[i][j] = 1;
else {
if (s[i] == s[j]) {
if (i + 1 == j) f[i][j] = 1;
else f[i][j] = f[i+1][j-1];
}
else f[i][j] = 0;
}
}
}
int res = 0;
fori(i,1,n) fori(j,i,n) res += f[i][j];
return res;
}
void solve() {
int res = calc();
fori(i,1,n) {
char c = s[i];
fori(j,0,25) {
if (s[i] - 'a' == j) continue;
s[i] = char(j + 'a');
// if(calc() > res) {
// cout << i << ' ' << s[i] << '\n';
// }
res = max(res, calc());
}
s[i] = c;
}
cout << res;
}
}
ll Total_Result;
namespace tester {
int f[5005][5005];
int calc() {
ford(i,n,1) {
fori(j,i,n) {
if (j == i) f[i][j] = 1;
else {
if (s[i] == s[j]) {
if (i + 1 == j) f[i][j] = 1;
else f[i][j] = f[i+1][j-1];
}
else f[i][j] = 0;
}
}
}
int res = 0;
fori(i,1,n) fori(j,i,n) res += f[i][j];
return res;
}
void solve() {
int cs = -1, sum = 0;
fori(i,2,n-1) {
if (s[i-1] == s[i+1]) {
int j = i-1;
while(j - 1 >= 1 && s[j-1] == s[j]) j --;
int j1 = i+1;
while(j1 + 1 <= n && s[j1 + 1] == s[j1]) j1 ++;
if (j1 - j + 1 > sum) {
cs = i;
sum = j1 - j + 1;
}
}
}
int res = calc();
if (1){
int sum1 = 0;
int cs1 = 0, cs2 = n + 1;
for(int i = 1; i <= n;) {
int j1 = i;
while(j1 + 1 <= n && s[j1 + 1] == s[i]) j1 ++;
if (sum1 < j1 - i + 1) {
sum1 = j1 - i + 1;
cs1 = i - 1;
cs2 = j1 + 1;
}
i = j1 + 1;
}
if (cs1 >= 1) {
char c = s[cs1];
s[cs1] = s[cs1 + 1];
res = max(res, calc());
s[cs1] = c;
}
if (cs2 <= n) {
char c = s[cs2];
s[cs2] = s[cs2-1];
res = max(res, calc());
s[cs2] = c;
}
Total_Result = max(Total_Result, 1ll * res);
}
if (cs != -1){
s[cs] = s[cs-1];
res = max(res, calc());
Total_Result = max(Total_Result, 1ll * res);
}
}
}
namespace sub2 {
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define TRACE(x) cerr << #x << " = " << x << endl
#define _ << " " <<
typedef pair<int, int> point;
const ll MOD = 1e9 + 7;
const ll BAZA = 1307;
string s;
int h[maxn], h_[maxn], pot[maxn];
void calcHash(){
pot[0] = 1;
h[0] = s[0];
FOR(i, 1, (int)s.size()){
h[i] = ((ll)h[i - 1] * BAZA + s[i]) % MOD;
pot[i] = (ll)pot[i - 1] * BAZA % MOD;
}
h_[0] = s[s.size() - 1];
for(int i = s.size() - 2, cnt = 1; i >= 0; --i, ++cnt)
h_[cnt] = ((ll)h_[cnt - 1] * BAZA + s[i]) % MOD;
}
ll calc(ll x, ll y){
ll k = 0;
if(x) k = (ll)h[x - 1] * pot[y] % MOD;
return ((((ll)h[x + y - 1] - k) % MOD) + MOD) % MOD;
}
ll calc_(ll x, ll y){
ll k = 0;
if(x) k = (ll)h_[x - 1] * pot[y] % MOD;
return ((((ll)h_[x + y - 1] - k) % MOD) + MOD) % MOD;
}
ll cntDec[maxn];
ll decrease[maxn];
ll increase[maxn], letInc[maxn][30];
void solve(){
ios_base::sync_with_stdio(false); cin.tie(0),
s = BASE_STRING;
calcHash();
ll sol = 0;
int len = s.size();
REP(i, len){
//neparni
ll lo = 1, hi = min(i + 1, len - i);
while(lo < hi){
ll mid = (lo + hi + 1) >> 1;
/*if(i + mid - 1 >= s.size() || len - i - 1 + mid - 1 >= s.size()){
assert(s.size() == 0);
}*/
if(calc(i, mid) == calc_(len - i - 1, mid))
lo = mid;
else
hi = mid - 1;
}
cntDec[i - lo + 1] ++;
cntDec[i + 1] -= 2;
cntDec[i + lo + 1] ++;
sol += lo;
increase[i] += lo;
ll jump = lo + 1;
lo = 0, hi = max(0LL, min(i + 1, len - i) - jump);
while(lo < hi){
ll mid = (lo + hi + 1) >> 1;
/*if(i + jump + mid - 1 >= s.size() || len - i + jump - 1 + mid - 1 >= s.size()){
assert(s.size() == 0);
}*/
if(calc(i + jump, mid) == calc_(len - i + jump - 1, mid))
lo = mid;
else
hi = mid - 1;
}
letInc[i + jump - 1][s[i - jump + 1] - 'a'] += lo + 1;
letInc[i - jump + 1][s[i + jump - 1] - 'a'] += lo + 1;
if(i == len - 1) continue;
//neparni
lo = 0, hi = max(0, min(i + 1, len - i - 1));
while(lo < hi){
ll mid = (lo + hi + 1) >> 1;
/*if(i + 1 + mid - 1 >= s.size() || len - i - 1 - mid + 1 >= s.size()){
assert(s.size() == 0);
}*/
if(calc(i + 1, mid) == calc_(len - i - 1, mid))
lo = mid;
else
hi = mid - 1;
}
sol += lo;
if(lo){
cntDec[i - lo + 1] ++;
cntDec[i + 1] --;
cntDec[i + 2] --;
cntDec[i + lo + 2] ++;
}
jump = lo + 1;
lo = 0, hi = max(0LL, min(i + 1, len - i - 1) - jump);
while(lo < hi){
ll mid = (lo + hi + 1) >> 1;
/*if(i + jump + 1 + mid - 1 >= s.size() || len - i + jump - 1 + mid - 1 >= s.size()){
assert(s.size() == 0);
}*/
if(calc(i + jump + 1, mid) == calc_(len - i + jump - 1, mid))
lo = mid;
else
hi = mid - 1;
}
letInc[i + jump][s[i - jump + 1] - 'a'] += lo + 1;
letInc[i - jump + 1][s[i + jump] - 'a'] += lo + 1;
}
ll cnt = 0, curr = 0;
REP(i, len){
cnt += cntDec[i];
curr += cnt;
decrease[i] = curr;
}
ll best = 0;
REP(i, len)
REP(j, 26){
best = max(best, increase[i] + letInc[i][j] - decrease[i]);
}
cout << sol + best;
}
}
void solve() {
Total_Result = n;
if (n <= 100) sub1::solve();
else if (n <= 5000)
sub2::solve();
else {
tester::solve();
cout << Total_Result;
}
}
int main () {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if (fopen(Task".inp", "r")) {
freopen(Task".inp", "r", stdin);
freopen(Task".out", "w", stdout);
}
read();
solve();
cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
return 0;
}
Compilation message
palinilap.cpp: In function 'int main()':
palinilap.cpp:308:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
308 | freopen(Task".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
palinilap.cpp:309:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
309 | freopen(Task".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
2392 KB |
Output is correct |
| 2 |
Correct |
22 ms |
2392 KB |
Output is correct |
| 3 |
Correct |
20 ms |
2556 KB |
Output is correct |
| 4 |
Correct |
23 ms |
2396 KB |
Output is correct |
| 5 |
Correct |
17 ms |
2396 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
8796 KB |
Output is correct |
| 2 |
Correct |
2 ms |
8796 KB |
Output is correct |
| 3 |
Correct |
3 ms |
8796 KB |
Output is correct |
| 4 |
Correct |
2 ms |
8796 KB |
Output is correct |
| 5 |
Correct |
3 ms |
8796 KB |
Output is correct |
| 6 |
Correct |
3 ms |
8792 KB |
Output is correct |
| 7 |
Correct |
3 ms |
8792 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
6 ms |
5212 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
