Submission #679862

#	Time	Username	Problem	Language	Result	Execution time	Memory
679862		peijar	Palindromic Partitions (CEOI17_palindromic)	C++17	60 / 100	10037 ms	31204 KiB

palindromic

#include <bits/stdc++.h>
#define int long long
using namespace std;

namespace std {
template <typename T> ostream &operator<<(ostream &out, const vector<T> &vec) {
  out << "[";
  for (int i = 0; i < (int)vec.size(); ++i) {
    out << vec[i];
    if (i + 1 < (int)vec.size())
      out << ", ";
  }
  return out << "]";
}
} // namespace std

void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
  cout << ' ' << H;
  dbg_out(T...);
}

#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

template <const int32_t MOD> struct ModInt {
  int32_t x;
  ModInt() : x(0) {}
  ModInt(long long u) : x(u % MOD) {
    if (x < 0)
      x += MOD;
  }
  friend bool operator==(const ModInt &a, const ModInt &b) {
    return a.x == b.x;
  }
  friend bool operator!=(const ModInt &a, const ModInt &b) {
    return a.x != b.x;
  }
  friend bool operator<(const ModInt &a, const ModInt &b) { return a.x < b.x; }
  friend bool operator>(const ModInt &a, const ModInt &b) { return a.x > b.x; }
  friend bool operator<=(const ModInt &a, const ModInt &b) {
    return a.x <= b.x;
  }
  friend bool operator>=(const ModInt &a, const ModInt &b) {
    return a.x >= b.x;
  }
  static ModInt sign(long long k) {
    return ((k & 1) ? ModInt(MOD - 1) : ModInt(1));
  }

  ModInt &operator+=(const ModInt &m) {
    x += m.x;
    if (x >= MOD)
      x -= MOD;
    return *this;
  }
  ModInt &operator-=(const ModInt &m) {
    x -= m.x;
    if (x < 0LL)
      x += MOD;
    return *this;
  }
  ModInt &operator*=(const ModInt &m) {
    x = (1LL * x * m.x) % MOD;
    return *this;
  }

  friend ModInt operator-(const ModInt &a) {
    ModInt res(a);
    if (res.x)
      res.x = MOD - res.x;
    return res;
  }
  friend ModInt operator+(const ModInt &a, const ModInt &b) {
    return ModInt(a) += ModInt(b);
  }
  friend ModInt operator-(const ModInt &a, const ModInt &b) {
    return ModInt(a) -= ModInt(b);
  }
  friend ModInt operator*(const ModInt &a, const ModInt &b) {
    return ModInt(a) *= ModInt(b);
  }

  static long long fp(long long u, long long k) {
    long long res = 1LL;
    while (k > 0LL) {
      if (k & 1LL)
        res = (res * u) % MOD;
      u = (u * u) % MOD;
      k /= 2LL;
    }
    return res;
  }

  static constexpr int mod() { return MOD; }

  ModInt fastpow(long long k) { return ModInt(fp(x, k)); }
  ModInt inv() {
    assert(x);
    return ModInt(fp(x, MOD - 2));
  }
  ModInt &operator/=(const ModInt &m) { return *this *= ModInt(m).inv(); }
  friend ModInt operator/(const ModInt &a, const ModInt &b) {
    return ModInt(a) *= ModInt(b).inv();
  }

  friend ostream &operator<<(ostream &out, const ModInt &a) {
    return out << a.x;
  }
  friend istream &operator>>(istream &in, ModInt &a) { return in >> a.x; }
};

const int MOD1 = 1e9 + 9, MOD2 = 1e9 + 7;

template <typename T1, typename T2> struct ModPair {
  T1 x;
  T2 y;

  ModPair() : x(0), y(0) {}

  ModPair(int u) : x(u), y(u) {}

  ModPair(T1 _x, T2 _y) : x(_x), y(_y) {}

  ModPair &operator+=(const ModPair &other) {
    x += other.x;
    y += other.y;
    return *this;
  }

  ModPair &operator*=(const ModPair &other) {
    x *= other.x;
    y *= other.y;
    return *this;
  }

  ModPair &operator-=(const ModPair &other) {
    x -= other.x;
    y -= other.y;
    return *this;
  }

  friend ModPair operator+(const ModPair &a, const ModPair &b) {
    return ModPair(a) += ModPair(b);
  }
  friend ModPair operator-(const ModPair &a, const ModPair &b) {
    return ModPair(a) -= ModPair(b);
  }
  friend ModPair operator*(const ModPair &a, const ModPair &b) {
    return ModPair(a) *= ModPair(b);
  }

  bool operator<(const ModPair &o) const { return pair(x, y) < pair(o.x, o.y); }
  bool operator>(const ModPair &o) const { return pair(x, y) > pair(o.x, o.y); }
  bool operator<=(const ModPair &o) const {
    return pair(x, y) <= pair(o.x, o.y);
  }
  bool operator>=(const ModPair &o) const {
    return pair(x, y) >= pair(o.x, o.y);
  }
  bool operator==(const ModPair &o) const {
    return pair(x, y) == pair(o.x, o.y);
  }

  ModPair inv() { return ModPair(x.inv(), y.inv()); };
};

using H = ModPair<ModInt<MOD1>, ModInt<MOD2>>;
const int BASE = 311;

struct Hashes {
  vector<H> po, pref, invPo;

  Hashes(string s) {
    int n = s.size();
    po.resize(n);
    invPo.resize(n);
    pref.resize(n + 1);
    po[0] = 1;
    for (int i = 1; i < n; ++i)
      po[i] = po[i - 1] * BASE;
    invPo[n - 1] = po[n - 1].inv();
    for (int i = n - 1; i > 0; --i)
      invPo[i - 1] = invPo[i] * BASE;
    for (int i = 0; i < n; ++i)
      pref[i + 1] = pref[i] + po[i] * s[i];
  }

  H getHsh(int deb, int fin) { return (pref[fin] - pref[deb]) * invPo[deb]; }
};

void solve() {
  string s;
  cin >> s;
  int N = s.size();
  if (N == 1) {
    cout << 1 << '\n';
    return;
  }
  dbg(s, N);
  string L = s.substr(0, N / 2);
  string R = s.substr((N + 1) / 2, N / 2);
  Hashes hashL(L), hashR(R);
  dbg(L, R);

  vector<int> dp(N / 2 + 1);
  dp[0] = N % 2;
  for (int lft = 1; lft <= N / 2; ++lft) {
    dp[lft] = 1;
    for (int take = 1; take <= lft; ++take)
      if (hashL.getHsh(N / 2 - lft, N / 2 - lft + take) ==
          hashR.getHsh(lft - take, lft))
        dp[lft] = max(dp[lft], dp[lft - take] + 2);
  }

  cout << dp[N / 2] << '\n';
}

signed main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int nbTests;
  cin >> nbTests;
  for (int iTest(0); iTest < nbTests; ++iTest)
    solve();
}

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 0 / 40