Submission #615465

#	Time	Username	Problem	Language	Result	Execution time	Memory
615465		abc864197532	Palindromes (APIO14_palindrome)	C++17	73 / 100	46 ms	48172 KiB

palindrome

#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define pii pair <int, int>
#define X first
#define Y second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
    cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
    for (; l != r; ++l) cout << *l << " \n"[l + 1 == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
    return o >> a.X >> a.Y;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
    return o << '(' << a.X << ", " << a.Y << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
    bool is = false;
    if (a.empty()) return o << "{}";
    for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
    return o << '}';
}
template <typename T> struct vv : vector <vector <T>> {
    vv (int n, int m, T v) : vector <vector <T>> (n, vector <T>(m, v)) {}
    vv (int n, int m) : vector <vector <T>> (n, vector <T>(m)) {}
    vv () {}
};
template <typename T> struct vvv : vector <vv <T>> {
    vvv (int n, int m, int k, T v) : vector <vv <T>> (n, vv <T>(m, k, v)) {}
    vvv (int n, int m, int k) : vector <vv <T>> (n, vv <T>(m, k)) {}
    vvv () {}
};
#ifdef Doludu
#define test(args...) abc("[" + string(#args) + "]", args)
#define owo freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#else
#define test(args...) void(0)
#define owo ios::sync_with_stdio(false); cin.tie(0)
#endif
const int mod = 998244353, N = 200005, logN = 18, G = 3;

struct PAM {
    int ch[N][26], cnt[N], fail[N], len[N], sz;
    string s;
    // 0 -> even root, 1 -> odd root
    PAM (string _s) : s(_s) {
        sz = 0;
        extend(), extend();
        len[0] = 0, fail[0] = 1, len[1] = -1;
        int lst = 1;
        for (int i = 0; i < s.length(); ++i) {
            while (s[i - len[lst] - 1] != s[i])
                lst = fail[lst];
            if (!ch[lst][s[i] - 'a'])  {
                int idx = extend();
                len[idx] = len[lst] + 2;
                int now = fail[lst];
                while (s[i - len[now] - 1] != s[i])
                    now = fail[now];
                fail[idx] = ch[now][s[i] - 'a'];
                ch[lst][s[i] - 'a'] = idx;
            }
            lst = ch[lst][s[i] - 'a'], cnt[lst]++;
        }
    }
    int extend() {
        fill(ch[sz], ch[sz] + 26, 0), sz++;
        return sz - 1;
    }
    lli solve() {
        for (int i = sz - 1; i > 1; --i) {
            cnt[fail[i]] += cnt[i];
        }
        lli ans = 0;
        for (int i = 2; i < sz; ++i) {
            ans = max(ans, 1ll * len[i] * cnt[i]);
        }
        return ans;
    }
};

int main () {
    owo;
    string s;
    cin >> s;
    PAM solver(s);
    cout << solver.solve() << '\n';
}

Compilation message (stderr)

palindrome.cpp: In constructor 'PAM::PAM(std::string)':
palindrome.cpp:59:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |         for (int i = 0; i < s.length(); ++i) {
      |                         ~~^~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 26 / 26
• Subtask 5: 0 / 27