#include<bits/stdc++.h>
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long ll;
#define int ll
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define pb push_back
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define mispertion ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define F first
#define S second
#define getlast(s) (*s.rbegin())
#define debg cout << "OK\n"
const ld PI = 3.1415926535;
const int N = 2e5 + 2;
const int M = 7e6 + 1;
int mod0 = 1e9+7, mod1 = 1e9+9;
const int infi = INT_MAX;
const ll infl = LLONG_MAX;
const int P = 31;
int mult(int a, int b, int mod) {
return a * 1LL * b % mod;
}
int sum(int a, int b, int mod) {
a %= mod;
if (a + b < 0)
return a + b + mod;
if (a + b >= mod)
return a + b - mod;
return a + b;
}
ll binpow(ll a, ll n, int mod) {
if (n == 0)
return 1;
if (n % 2 == 1) {
return binpow(a, n - 1, mod) * a % mod;
} else {
ll b = binpow(a, n / 2, mod);
return b * b % mod;
}
}
int p = 31;
int pp[N][2], ip[N][2];
int hss[N][2], hsr[N][2];
vector<pair<int, pii>> rs[N], ls[N];
vector<int> rss[N], lss[N];
string s;
pii gets(int l, int r){
return {mult(sum(hss[r][0], -hss[l - 1][0], mod0), ip[l - 1][0], mod0),
mult(sum(hss[r][1], -hss[l - 1][1], mod1), ip[l - 1][1], mod1)};
}
pii getr(int l, int r){
return {mult(sum(hsr[l][0], -hsr[r + 1][0], mod0), ip[sz(s) - r - 1][0], mod0),
mult(sum(hsr[l][1], -hsr[r + 1][1], mod1), ip[sz(s) - r - 1][1], mod1)};
}
int stupid(string s){
int ans = -infl;
for(int i = 1; i < sz(s); i++){
for(char c = 'a'; c <= 'z'; c++){
char tmp = s[i];
s[i] = c;
int cur = 0;
for(int l = 1; l < sz(s); l++){
for(int r = l; r < sz(s); r++){
bool ok = true;
for(int i = 1; i <= (r - l + 1); i++)
if(s[l + i - 1] != s[r - i + 1])
ok = false;
cur += ok;
}
}
ans = max (ans, cur);
s[i] = tmp;
}
}
for(int i = 1; i < sz(s); i++){
for(char c = 'a'; c <= 'z'; c++){
char tmp = s[i];
s[i] = c;
int cur = 0;
for(int l = 1; l < sz(s); l++){
for(int r = l; r < sz(s); r++){
bool ok = true;
for(int i = 1; i <= (r - l + 1); i++)
if(s[l + i - 1] != s[r - i + 1])
ok = false;
cur += ok;
}
}
if(cur == ans)
cout << i << ' ' << c << '\n';
s[i] = tmp;
}
}
return ans;
}
void solve(){
cin >> s;
s = "#" + s;
hss[0][0] = 0;
hss[0][1] = 0;
for(int i = 1; i < sz(s); i++){
hss[i][0] = sum(hss[i - 1][0], mult(s[i] - 'a' + 1, pp[i - 1][0], mod0), mod0);
hss[i][1] = sum(hss[i - 1][1], mult(s[i] - 'a' + 1, pp[i - 1][1], mod1), mod1);
}
hsr[sz(s)][0] = 0;
hsr[sz(s)][1] = 0;
for(int i = sz(s) - 1; i >= 1; i--){
hsr[i][0] = sum(hsr[i + 1][0], mult(pp[sz(s) - i - 1][0], s[i] - 'a' + 1, mod0), mod0);
hsr[i][1] = sum(hsr[i + 1][1], mult(pp[sz(s) - i - 1][1], s[i] - 'a' + 1, mod1), mod1);
}
vector<pii> kakoizhegovnokodyapishu = {};
for(int i = 1; i < sz(s); i++){
int lo = 1, hi = min(i, sz(s) - i) + 1;
while(lo + 1 < hi){
int m = (lo + hi) / 2;
if(gets(i - m + 1, i) == getr(i, i + m - 1))
lo = m;
else
hi = m;
}
kakoizhegovnokodyapishu.pb({i - lo + 1, i + lo - 1});
if(i < sz(s) - 1 && s[i] == s[i + 1]){
lo = 1, hi = min(i, sz(s) - i - 1) + 1;
while(lo + 1 < hi){
int m = (lo + hi) / 2;
if(gets(i - m + 1, i) == getr(i + 1, i + m))
lo = m;
else
hi = m;
}
kakoizhegovnokodyapishu.pb({i - lo + 1, i + lo});
}
}
int ret = 0;
for(auto e : kakoizhegovnokodyapishu){
int l = e.F, r = e.S;
//cout << l << ' ' << r << '\n';
ret += ((r - l + 2) / 2);
rss[r].pb(l);
lss[l].pb(r);
if(l == r)
continue;
if((r - l + 1) % 2){
int m = (l + r) / 2;
ls[l].pb({m - 1, {1, 1}});
rs[m - 1].pb({l, {1, 1}});
ls[m + 1].pb({r, {r - m, -1}});
rs[r].pb({m + 1, {r - m, -1}});
}else{
int m1 = (l + r) / 2, m2 = m1 + 1;
ls[l].pb({m1, {1, 1}});
rs[m1].pb({l, {1, 1}});
ls[m2].pb({r, {r - m1, -1}});
rs[r].pb({m2, {r - m1, -1}});
}
}
//cout << ret << '\n';
int td[sz(s)];
int ca = 0, cd = 0;
for(int i = 1; i < sz(s); i++){
ca += cd;
for(auto e : ls[i]){
ca += e.S.F;
cd += e.S.S;
}
td[i] = ca;
for(auto e : rs[i]){
int r = i, l = e.F;
ca -= (e.S.F + (r - l) * e.S.S);
cd -= e.S.S;
}
}
int ans = ret;
for(int i = 1; i < sz(s); i++){
for(char c = 'a'; c <= 'z'; c++){
if(c == s[i])
continue;
int cur = ret - td[i];
//cout << i << ' ' << c << '\n';
//cout << '\t' << cur << '\n';
if(i < sz(s) - 1 && s[i + 1] == c){
int lo = 0, hi = min(i, sz(s) - i - 1);
while(lo + 1 < hi){
int m = (lo + hi) / 2;
if(gets(i - m, i - 1) == getr(i + 2, i + 1 + m))
lo = m;
else
hi = m;
}
cur += (lo + 1);
}
if(i - 1 >= 1 && s[i - 1] == c){
int lo = 0, hi = min(i - 1, sz(s) - i);
while(lo + 1 < hi){
int m = (lo + hi) / 2;
if(gets(i - m - 1, i - 2) == getr(i + 1, i + m))
lo = m;
else
hi = m;
}
cur += (lo + 1);
}
for(auto e : rss[i - 1]){
int l = e, r = i - 1;
if(c == s[l - 1]){
int lo = 0, hi = min(l - 1, sz(s) - i);
//cout << '\t' << l << ' ' << r << '\n';
while(lo + 1 < hi){
int m = (lo + hi) / 2;
if(gets(l - 1 - m, l - 2) == getr(i + 1, i + m))
lo = m;
else
hi = m;
}
//cout << '\t' << lo + 1 << '\n';
cur += (lo + 1);
}
}
for(auto e : lss[i + 1]){
int l = i + 1, r = e;
if(r + 1 != sz(s) && c == s[r + 1]){
int lo = 0, hi = min(l - 1, sz(s) - r - 1);
//cout << '\t' << l << ' ' << r << '\n';
while(lo + 1 < hi){
int m = (lo + hi) / 2;
if(gets(l - 1 - m, l - 2) == getr(r + 2, r + 1 + m))
lo = m;
else
hi = m;
}
//cout << '\t' << lo + 1 << '\n';
cur += (lo + 1);
}
}
//cout << '\t' << cur << '\n';
ans = max(ans, cur);
}
}
//cout << stupid(s) << '\n';
cout << ans << '\n';
}
signed main() {
mispertion;
pp[0][0] = 1, pp[0][1] = 1, ip[0][0] = 1, ip[0][1] = 1;
for(int i = 1; i < N; i++){
pp[i][0] = mult(pp[i - 1][0], p, mod0);
pp[i][1] = mult(pp[i - 1][1], p, mod1);
ip[i][0] = binpow(pp[i][0], mod0 - 2, mod0);
ip[i][1] = binpow(pp[i][1], mod1 - 2, mod1);
}
int t = 1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
Compilation message
palinilap.cpp: In function 'void solve()':
palinilap.cpp:221:28: warning: unused variable 'r' [-Wunused-variable]
221 | int l = e, r = i - 1;
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
175 ms |
29592 KB |
Output is correct |
| 2 |
Correct |
174 ms |
29592 KB |
Output is correct |
| 3 |
Correct |
174 ms |
29596 KB |
Output is correct |
| 4 |
Correct |
174 ms |
29592 KB |
Output is correct |
| 5 |
Correct |
174 ms |
29524 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
183 ms |
31528 KB |
Output is correct |
| 2 |
Correct |
186 ms |
31704 KB |
Output is correct |
| 3 |
Correct |
191 ms |
30364 KB |
Output is correct |
| 4 |
Correct |
184 ms |
30040 KB |
Output is correct |
| 5 |
Correct |
189 ms |
30288 KB |
Output is correct |
| 6 |
Correct |
193 ms |
31060 KB |
Output is correct |
| 7 |
Correct |
189 ms |
30036 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
694 ms |
54448 KB |
Output is correct |
| 2 |
Correct |
496 ms |
72112 KB |
Output is correct |
| 3 |
Correct |
529 ms |
72588 KB |
Output is correct |
| 4 |
Correct |
662 ms |
50212 KB |
Output is correct |
| 5 |
Correct |
659 ms |
49328 KB |
Output is correct |
| 6 |
Correct |
674 ms |
49328 KB |
Output is correct |
| 7 |
Correct |
663 ms |
50088 KB |
Output is correct |
| 8 |
Correct |
419 ms |
72176 KB |
Output is correct |
| 9 |
Correct |
668 ms |
49760 KB |
Output is correct |
| 10 |
Correct |
667 ms |
49896 KB |
Output is correct |
| 11 |
Correct |
500 ms |
72116 KB |
Output is correct |
| 12 |
Correct |
717 ms |
72444 KB |
Output is correct |
| 13 |
Correct |
659 ms |
53544 KB |
Output is correct |
| 14 |
Correct |
660 ms |
49004 KB |
Output is correct |
| 15 |
Correct |
667 ms |
49888 KB |
Output is correct |
| 16 |
Correct |
587 ms |
71064 KB |
Output is correct |
| 17 |
Correct |
601 ms |
41400 KB |
Output is correct |
| 18 |
Correct |
660 ms |
50148 KB |
Output is correct |
| 19 |
Correct |
604 ms |
41148 KB |
Output is correct |
