#include <bits/stdc++.h>
#define forr(_a,_b,_c) for(_a = _b; _a <= _c; ++_a)
#define ford(_a,_b,_c) for(_a = (_b) + 1; _a --> _c;)
#define forf(_a,_b,_c) for(_a = _b; _a < _c; ++_a)
#define st first
#define nd second
#define ll long long
#define ull unsigned long long
#define pii pair <int,int>
#define pll pair <ll,ll>
#define piii pair <int,pii>
#define vi vector <int>
#define pb push_back
#define mp make_pair
#define all(x) begin(x),end(x)
#define file "test"
using namespace std;
const int N = 5e5 + 5;
const ll oo = 1e9;
const ll mod = 1e9 + 7;
const ll base = 33577;
ll h[2][N],pw[N];
ll get (int i, int l, int r){
return (h[i][r] - h[i][l - 1] * pw[r - l + 1] + mod * mod) % mod;
}
int i;
string s;
ll preadd[N],sufadd[N],res[N][26],pre[N],suf[N];
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> s;
int n = s.size();
pw[0] = 1;
string rs = s;
reverse(all(rs));
forr (i,1,n)
pw[i] = (pw[i - 1] * base) % mod,
h[0][i] = (h[0][i - 1] * base + s[i - 1]) % mod,
h[1][i] = (h[1][i - 1] * base + rs[i - 1]) % mod;
forr (i,1,n){
int l = 0, r = min (n - i,i - 1);
while (l < r){
int mid = (l + r + 1)/2;
if (get(0,i - mid,i) == get(1,n - i + 1 - mid,n - i + 1))
l = mid;
else r = mid - 1;
}
//cout << l << "\n";
preadd[i]++;
preadd[i + l + 1]--;
sufadd[i]++;
sufadd[i - l - 1]--;
if (i + l != n && i - l != 1){
int nl = l + 1, r = min(n - i,i - 1);
while (nl < r){
int mid = (nl + r + 1)/2;
//cout << i - mid << " " << i - l - 2 << " " << n - i + 1 - mid << " " << n - i - l - 1 << "\n";
// cout << get(0,i - mid,i - l - 2) << " " << get(1,n - i - mid + 1, n - i - l - 1) << "\n";
if (get(0,i - mid,i - l - 2) == get(1,n - i - mid + 1, n - i - l - 1))
nl = mid;
else r = mid - 1;
}
res[i - l][s[i + l] - 'a'] += nl - l;
res[i + l][s[i - l] - 'a'] += nl - l;
}
}
forr (i,1,n - 1){
int l = 0, r = min (n - i - 1,i - 1);
while (l < r){
int mid = (l + r + 1)/2;
//cout << i - mid << " " << i << " " << n - i - mid << " " << n - i << "\n";
if (get(0,i - mid,i) == get(1,n - i - mid,n - i))
l = mid;
else r = mid - 1;
}
if (s[i] != s[i - 1])
l = -1;
//cout << l << "\n";
if (l != -1){
preadd[i + 1]++;
preadd[i + l + 2]--;
sufadd[i]++;
sufadd[i - l - 1]--;
}
if (i + l != n && i - l != 1){
int nl = l + 1, r = min(n - i - 1,i - 1);
//cout << nl << " " << r << "\n";
while (nl < r){
int mid = (nl + r + 1)/2;
//cout << i - mid << " " << i - l - 2 << " " << n - i - mid << " " << n - i - l - 2 << "\n";
//cout << get(0,i - mid,i - l - 2) << " " << get(1,n - i - mid, n - i - l - 2) << "\n";
if (get(0,i - mid,i - l - 2) == get(1,n - i - mid, n - i - l - 2))
nl = mid;
else r = mid - 1;
}
res[i - nl][s[i + nl + 1] - 'a'] += r - l;
res[i + nl + 1][s[i - nl] - 'a'] += r - l;
//cout << i << " " << l << " " << r << "\n";
}
}
forr (i,1,n){
preadd[i] += preadd[i - 1];
pre[i] += preadd[i] + pre[i - 1];
}
ford (i,n,1){
sufadd[i] += sufadd[i + 1];
suf[i] = sufadd[i] + suf[i + 1];
}
ll ans = 0,j;
forr (i,1,n){
ans = max (ans,max(suf[i + 1] + pre[i],pre[i - 1] + suf[i]));
ll mx = 0;
forr (j,0,25)
mx = max (mx,res[i][j]);
ans = max (ans,pre[i - 1] + suf[i + 1] + mx);
}
cout << ans << "\n";
return 0;
}
/*
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
8540 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
10840 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
42 ms |
35408 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
