Submission #958026

#	Time	Username	Problem	Language	Result	Execution time	Memory
958026		riariti	Palindromes (APIO14_palindrome)	C++17	100 / 100	53 ms	66656 KiB

palindrome

#line 1 "Palindromes.cpp"
#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using u32 = unsigned int;
using u64 = unsigned long long;
using i128 = __int128;
using u128 = unsigned __int128;

template <class T> constexpr T infty = 0;
template <> constexpr int infty<int> = 1'000'000'000;
template <> constexpr ll infty<ll> = ll(infty<int>) * infty<int> * 2;
template <> constexpr u32 infty<u32> = infty<int>;
template <> constexpr u64 infty<u64> = infty<ll>;
template <> constexpr i128 infty<i128> = i128(infty<ll>) * infty<ll>;
template <> constexpr double infty<double> = infty<ll>;
template <> constexpr long double infty<long double> = infty<ll>;

using pi = pair<ll, ll>;
using vi = vector<ll>;
template <class T> using vc = vector<T>;
template <class T> using vvc = vector<vc<T>>;
template <class T> using vvvc = vector<vvc<T>>;
template <class T> using vvvvc = vector<vvvc<T>>;
template <class T> using vvvvvc = vector<vvvvc<T>>;
template <class T> using pq = priority_queue<T>;
template <class T> using pqg = priority_queue<T, vector<T>, greater<T>>;

#define vv(type, name, h, ...)                                                 \
    vector<vector<type>> name(h, vector<type>(__VA_ARGS__))
#define vvv(type, name, h, w, ...)                                             \
    vector<vector<vector<type>>> name(                                         \
        h, vector<vector<type>>(w, vector<type>(__VA_ARGS__)))
#define vvvv(type, name, a, b, c, ...)                                         \
    vector<vector<vector<vector<type>>>> name(                                 \
        a, vector<vector<vector<type>>>(                                       \
               b, vector<vector<type>>(c, vector<type>(__VA_ARGS__))))

// https://trap.jp/post/1224/
#define FOR1(a) for (ll _ = 0; _ < ll(a); ++_)
#define FOR2(i, a) for (ll i = 0; i < ll(a); ++i)
#define FOR3(i, a, b) for (ll i = a; i < ll(b); ++i)
#define FOR4(i, a, b, c) for (ll i = a; i < ll(b); i += (c))
#define FOR1_R(a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR2_R(i, a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR3_R(i, a, b) for (ll i = (b)-1; i >= ll(a); --i)
#define overload4(a, b, c, d, e, ...) e
#define overload3(a, b, c, d, ...) d
#define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define FOR_R(...) overload3(__VA_ARGS__, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__)

#define FOR_subset(t, s)                                                       \
    for (ll t = (s); t >= 0; t = (t == 0 ? -1 : (t - 1) & (s)))
#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define elif else if

#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second

#define stoi stoll

int popcnt(int x) { return __builtin_popcount(x); }
int popcnt(u32 x) { return __builtin_popcount(x); }
int popcnt(ll x) { return __builtin_popcountll(x); }
int popcnt(u64 x) { return __builtin_popcountll(x); }
int popcnt_mod_2(int x) { return __builtin_parity(x); }
int popcnt_mod_2(u32 x) { return __builtin_parity(x); }
int popcnt_mod_2(ll x) { return __builtin_parityll(x); }
int popcnt_mod_2(u64 x) { return __builtin_parityll(x); }
// (0, 1, 2, 3, 4) -> (-1, 0, 1, 1, 2)
int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(u32 x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
int topbit(u64 x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
// (0, 1, 2, 3, 4) -> (-1, 0, 1, 0, 2)
int lowbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int lowbit(u32 x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int lowbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); }
int lowbit(u64 x) { return (x == 0 ? -1 : __builtin_ctzll(x)); }

template <typename T> T floor(T a, T b) {
    return a / b - (a % b && (a ^ b) < 0);
}
template <typename T> T ceil(T x, T y) { return floor(x + y - 1, y); }
template <typename T> T bmod(T x, T y) { return x - y * floor(x, y); }
template <typename T> pair<T, T> divmod(T x, T y) {
    T q = floor(x, y);
    return {q, x - q * y};
}

template <typename T, typename U> T SUM(const vector<U> &A) {
    T sm = 0;
    for (auto &&a : A)
        sm += a;
    return sm;
}

#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define LB(c, x) distance((c).begin(), lower_bound(all(c), (x)))
#define UB(c, x) distance((c).begin(), upper_bound(all(c), (x)))
#define UNIQUE(x)                                                              \
    sort(all(x)), x.erase(unique(all(x)), x.end()), x.shrink_to_fit()

template <typename T> T POP(deque<T> &que) {
    T a = que.front();
    que.pop_front();
    return a;
}
template <typename T> T POP(pq<T> &que) {
    T a = que.top();
    que.pop();
    return a;
}
template <typename T> T POP(pqg<T> &que) {
    T a = que.top();
    que.pop();
    return a;
}
template <typename T> T POP(vc<T> &que) {
    T a = que.back();
    que.pop_back();
    return a;
}

template <typename F>
ll binary_search(F check, ll ok, ll ng, bool check_ok = true) {
    if (check_ok)
        assert(check(ok));
    while (abs(ok - ng) > 1) {
        auto x = (ng + ok) / 2;
        (check(x) ? ok : ng) = x;
    }
    return ok;
}
template <typename F>
double binary_search_real(F check, double ok, double ng, int iter = 100) {
    FOR(iter) {
        double x = (ok + ng) / 2;
        (check(x) ? ok : ng) = x;
    }
    return (ok + ng) / 2;
}

template <class T, class S> inline bool chmax(T &a, const S &b) {
    return (a < b ? a = b, 1 : 0);
}
template <class T, class S> inline bool chmin(T &a, const S &b) {
    return (a > b ? a = b, 1 : 0);
}

// ? は -1
vc<int> s_to_vi(const string &S, char first_char) {
    vc<int> A(S.size());
    FOR(i, S.size()) { A[i] = (S[i] != '?' ? S[i] - first_char : -1); }
    return A;
}

template <typename T, typename U> vector<T> cumsum(vector<U> &A, int off = 1) {
    int N = A.size();
    vector<T> B(N + 1);
    FOR(i, N) { B[i + 1] = B[i] + A[i]; }
    if (off == 0)
        B.erase(B.begin());
    return B;
}

// stable sort
template <typename T> vector<int> argsort(const vector<T> &A) {
    vector<int> ids(len(A));
    iota(all(ids), 0);
    sort(all(ids),
         [&](int i, int j) { return (A[i] == A[j] ? i < j : A[i] < A[j]); });
    return ids;
}

// A[I[0]], A[I[1]], ...
template <typename T> vc<T> rearrange(const vc<T> &A, const vc<int> &I) {
    vc<T> B(len(I));
    FOR(i, len(I)) B[i] = A[I[i]];
    return B;
}

// palindromic tree を作る
template <int sigma> struct Palindromic_Tree {
    struct Node {
        std::array<int, sigma> TO;
        int link;
        int length;
        std::pair<int, int> pos;
        Node(int link, int length, int l, int r)
            : link(link), length(length), pos({l, r}) {
            std::fill(TO.begin(), TO.end(), -1);
        }
    };

    std::vector<Node> nodes;
    std::vector<int> path;

    template <typename STRING> Palindromic_Tree(const STRING &S, char off) {
        nodes.emplace_back(Node(-1, -1, 0, -1));
        nodes.emplace_back(Node(0, 0, 0, 0));
        int p = 0;
        FOR(i, len(S)) {
            path.eb(p);
            int x = S[i] - off;
            while (p) {
                int j = i - 1 - nodes[p].length;
                bool can = (j >= 0 && S[j] - off == x);
                if (!can) {
                    p = nodes[p].link;
                    continue;
                }
                break;
            }
            if (nodes[p].TO[x] != -1) {
                p = nodes[p].TO[x];
                continue;
            }
            int to = len(nodes);
            int l = i - 1 - nodes[p].length;
            int r = i + 1;
            nodes[p].TO[x] = to;

            int link;
            if (p == 0)
                link = 1;
            if (p != 0) {
                while (1) {
                    p = nodes[p].link;
                    int j = i - 1 - nodes[p].length;
                    bool can = (j >= 0 && S[j] - off == x) || (p == 0);
                    if (can)
                        break;
                }
                assert(nodes[p].TO[x] != -1);
                link = nodes[p].TO[x];
            }
            nodes.eb(Node(link, r - l, l, r));
            p = to;
        }
        path.eb(p);
    }

    // node ごとの出現回数
    vc<int> count() {
        vc<int> res(len(nodes));
        for (auto &&p : path)
            res[p]++;
        FOR_R(k, 1, len(nodes)) {
            int link = nodes[k].link;
            res[link] += res[k];
        }
        return res;
    }
};

constexpr std::int64_t inf = 2E18;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    std::string S;
    std::cin >> S;

    Palindromic_Tree<26> X(S, 'a');

    auto cnt = X.count();

    std::int64_t ans = -inf;
    for (int i = 2; i < X.nodes.size(); i++) {
        auto &&[l, r] = X.nodes[i].pos;

        ans = std::max(ans, static_cast<std::int64_t>(r - l) * cnt[i]);
    }

    std::cout << ans << "\n";

    return 0;
}

Compilation message (stderr)

Palindromes.cpp: In function 'int main()':
Palindromes.cpp:277:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Palindromic_Tree<26>::Node, std::allocator<Palindromic_Tree<26>::Node> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]

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