String/Manacher.h

• View this file on GitHub
• Last update: 2025-12-04 02:05:35+07:00

Depends on

• template.h

Verified with

• String/Yosupo/Enumerate_Palindromes.test.cpp

Code

#include "../template.h"

// Base = 1
// s = '$' + s;
// vector<int> odd = calc_odd(s);
// vector<int> even = calc_even(s);
// not count center as palindrome

vector<int> calc_odd(string &s) {
    int n = s.size();
    vector<int> d(n);
    int l = 1, r = 0;
    for (int i = 1; i < n; i++) {
        if (i > r) d[i] = 0;
        else d[i] = min(r-i, d[l+r-i]);
        while (i-d[i]-1 > 0 && i+d[i]+1 < n && s[i-d[i]-1] == s[i+d[i]+1]) {
            d[i]++;
        }
        if (i + d[i] > r) {
            l = i - d[i];
            r = i + d[i];
        }
    }
    return d;
}

vector<int> calc_even(string &s) {
    int n = s.size();
    vector<int> d(n);
    int l = 1, r = 0;
    for (int i = 1; i < n-1; i++) {
        int j = i+1;
        if (j > r) d[i] = 0;
        else d[i] = min(r-j+1, d[l+r-j]);
        while (i-d[i] >= 0 && j+d[i] < n && s[i-d[i]] == s[j+d[i]]) {
            d[i]++;
        }
        if (i + d[i] > r) {
            l = j - d[i];
            r = i + d[i];
        }
    }
    return d;
}

#line 2 "template.h"

#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define MOD (ll)(1e9+7)
#define all(x) (x).begin(),(x).end()
#define unique(x) x.erase(unique(all(x)), x.end())
#define INF32 ((1ull<<31)-1)
#define INF64 ((1ull<<63)-1)
#define inf (ll)1e18

#define vi vector<int>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second

const int mod = 998244353;

void solve();

int main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);
    // cin.exceptions(cin.failbit);
    // int t; cin >> t;
    // while(t--)
        solve();
    cerr << "\nTime run: " << 1000 * clock() / CLOCKS_PER_SEC << "ms" << '\n';
    return 0;
}
#line 2 "String/Manacher.h"

// Base = 1
// s = '$' + s;
// vector<int> odd = calc_odd(s);
// vector<int> even = calc_even(s);
// not count center as palindrome

vector<int> calc_odd(string &s) {
    int n = s.size();
    vector<int> d(n);
    int l = 1, r = 0;
    for (int i = 1; i < n; i++) {
        if (i > r) d[i] = 0;
        else d[i] = min(r-i, d[l+r-i]);
        while (i-d[i]-1 > 0 && i+d[i]+1 < n && s[i-d[i]-1] == s[i+d[i]+1]) {
            d[i]++;
        }
        if (i + d[i] > r) {
            l = i - d[i];
            r = i + d[i];
        }
    }
    return d;
}

vector<int> calc_even(string &s) {
    int n = s.size();
    vector<int> d(n);
    int l = 1, r = 0;
    for (int i = 1; i < n-1; i++) {
        int j = i+1;
        if (j > r) d[i] = 0;
        else d[i] = min(r-j+1, d[l+r-j]);
        while (i-d[i] >= 0 && j+d[i] < n && s[i-d[i]] == s[j+d[i]]) {
            d[i]++;
        }
        if (i + d[i] > r) {
            l = j - d[i];
            r = i + d[i];
        }
    }
    return d;
}

Back to top page