string/manacher.hpp

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• Last update: 2025-02-21 22:29:18+09:00
• Include: #include "string/manacher.hpp"

Verified with

• verify/yosupo/yosupo_enumerate_palindromes.test.cpp

Code

vector<int> manacher(const string& s) {
    int n = s.size();
    vector<int> ret(n);
    int i = 0, j = 0;
    while(i < n) {
        while(i - j >= 0 && i + j < n && s[i - j] == s[i + j]) j++;
        ret[i] = j;
        int k = 1;
        while(i - k >= 0 && k + ret[i - k] < j) ret[i + k] = ret[i - k], k++;
        i += k; j -= k;
    }
    return ret;
}

#line 1 "string/manacher.hpp"
vector<int> manacher(const string& s) {
    int n = s.size();
    vector<int> ret(n);
    int i = 0, j = 0;
    while(i < n) {
        while(i - j >= 0 && i + j < n && s[i - j] == s[i + j]) j++;
        ret[i] = j;
        int k = 1;
        while(i - k >= 0 && k + ret[i - k] < j) ret[i + k] = ret[i - k], k++;
        i += k; j -= k;
    }
    return ret;
}

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