#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ldb,ldb> pdd;
#define ff(i,a,b) for(int i = a; i <= b; i++)
#define fb(i,b,a) for(int i = b; i >= a; i--)
#define trav(a,x) for(auto& a : x)
#define sz(a) (int)(a).size()
#define fi first
#define se second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k) print the k-th smallest number in os(0-based)
const int mod = 1000000007;
const int inf = 1e9 + 5;
const int mxN = 200005;
int n;
string s;
ll cnt[mxN];
ll sum[mxN];
ll kol[mxN][26];
int add(int a, int b){ a += b; if(a >= mod)a -= mod; return a; }
int sub(int a, int b){ a -= b; if(a < 0)a += mod; return a; }
int mul(int a, int b){ return (1ll * a * b) % mod; }
int power(int a, int b){
if(!b)return 1;
int p = power(a, b / 2);
p = mul(p, p);
if(b % 2 == 1)p = mul(p, a);
return p;
}
int inv(int a){
return power(a, mod - 2);
}
const int p1 = 37;
int pw[mxN];
int invz[mxN];
int pref[mxN];
int getP(int l, int r){
return mul(sub(pref[r], (l == 0 ? 0 : pref[l - 1])), invz[l]);
}
int sufi[mxN];
int getS(int l, int r){
return mul(sub(sufi[l], sufi[r + 1]), invz[n - r - 1]);
}
int calc(int a, int b){
if(a < 0 || b >= n)return 0;
int l = 1, r = n, ans = 0;
while(l <= r){
int mid = (l + r) / 2;
if(a - mid + 1 >= 0 && b + mid - 1 < n && getP(a - mid + 1, a) == getS(b, b + mid - 1)){
ans = mid;
l = mid + 1;
}
else r = mid - 1;
}
return ans;
}
int main(){
cin.tie(0)->sync_with_stdio(0);
cin >> s; n = sz(s);
pw[0] = 1;
ff(i,1,n)pw[i] = mul(pw[i - 1], p1);
invz[n] = inv(pw[n]);
fb(i,n - 1,0)invz[i] = mul(invz[i + 1], p1);
ff(i,0,n - 1)pref[i] = add((i == 0 ? 0 : pref[i - 1]), mul(s[i] - 'a' + 1, pw[i]));
fb(i,n - 1,0)sufi[i] = add(sufi[i + 1], mul(s[i] - 'a' + 1, pw[n - i - 1]));
ll uk = 0;
ff(i,0,n - 1){
int l = 1, r = n, ans = 0;
while(l <= r){
int mid = (l + r) / 2;
if(i - mid + 1 >= 0 && i + mid - 1 < n && getP(i - mid + 1, i) == getS(i, i + mid - 1)){
ans = mid;
l = mid + 1;
}
else r = mid - 1;
}
cnt[i - ans + 1] -= 1; cnt[i] += 1;
sum[i - ans + 1] += (i - ans); sum[i] -= (i - ans);
cnt[i + 1] += 1; cnt[i + ans] -= 1;
sum[i + 1] -= (i + ans); sum[i + ans] += (i + ans);
uk += ans;
int a = i - ans;
int b = i + ans;
if(a < 0 || b >= n)continue;
int ima = 1 + calc(a - 1, b + 1);
kol[a][s[b] - 'a'] += ima;
kol[b][s[a] - 'a'] += ima;
}
ff(i,1,n - 1){
int l = 1, r = n, ans = 0;
while(l <= r){
int mid = (l + r) / 2;
if(i - mid + 1 >= 0 && i + mid - 1 < n && getP(i - mid, i - 1) == getS(i, i + mid - 1)){
ans = mid;
l = mid + 1;
}
else r = mid - 1;
}
uk += ans;
cnt[i - ans] -= 1; cnt[i] += 1;
sum[i - ans] += (i - ans - 1); sum[i] -= (i - ans - 1);
cnt[i] += 1; cnt[i + ans] -= 1;
sum[i] -= (i + ans); sum[i + ans] += (i + ans);
int a = i - ans - 1;
int b = i + ans;
if(a < 0 || b >= n)continue;
int ima = 1 + calc(a - 1, b + 1);
kol[a][s[b] - 'a'] += ima;
kol[b][s[a] - 'a'] += ima;
}
ff(i,1,n - 1){
cnt[i] += cnt[i - 1];
sum[i] += sum[i - 1];
}
ll rez = uk;
ff(i,0,n - 1){
ll mx = 0;
ff(j,0,25)mx = max(mx, kol[i][j]);
ll ans = uk + mx + 1ll * i * cnt[i] + sum[i];
rez = max(rez, ans);
}
cout << rez << '\n';
return 0;
}
/*
// probati bojenje sahovski
*/
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
2396 KB |
Output is correct |
| 2 |
Correct |
0 ms |
348 KB |
Output is correct |
| 3 |
Correct |
0 ms |
348 KB |
Output is correct |
| 4 |
Correct |
0 ms |
348 KB |
Output is correct |
| 5 |
Correct |
1 ms |
348 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
2 ms |
1628 KB |
Output is correct |
| 2 |
Correct |
2 ms |
1628 KB |
Output is correct |
| 3 |
Correct |
2 ms |
1628 KB |
Output is correct |
| 4 |
Correct |
1 ms |
1116 KB |
Output is correct |
| 5 |
Correct |
2 ms |
1628 KB |
Output is correct |
| 6 |
Correct |
2 ms |
1628 KB |
Output is correct |
| 7 |
Correct |
2 ms |
1688 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
51 ms |
24148 KB |
Output is correct |
| 2 |
Correct |
33 ms |
24668 KB |
Output is correct |
| 3 |
Correct |
39 ms |
24716 KB |
Output is correct |
| 4 |
Correct |
55 ms |
24576 KB |
Output is correct |
| 5 |
Correct |
50 ms |
24700 KB |
Output is correct |
| 6 |
Correct |
47 ms |
24656 KB |
Output is correct |
| 7 |
Correct |
46 ms |
24664 KB |
Output is correct |
| 8 |
Correct |
19 ms |
5592 KB |
Output is correct |
| 9 |
Correct |
60 ms |
24144 KB |
Output is correct |
| 10 |
Correct |
47 ms |
24660 KB |
Output is correct |
| 11 |
Correct |
34 ms |
24664 KB |
Output is correct |
| 12 |
Correct |
47 ms |
24660 KB |
Output is correct |
| 13 |
Correct |
49 ms |
24652 KB |
Output is correct |
| 14 |
Correct |
47 ms |
24660 KB |
Output is correct |
| 15 |
Correct |
51 ms |
24668 KB |
Output is correct |
| 16 |
Correct |
39 ms |
24664 KB |
Output is correct |
| 17 |
Correct |
45 ms |
24716 KB |
Output is correct |
| 18 |
Correct |
50 ms |
24664 KB |
Output is correct |
| 19 |
Correct |
44 ms |
24572 KB |
Output is correct |
