oj.uz

Submission #891638

# Submission time Handle Problem Language Result Execution time Memory
891638 2023-12-23T11:58:56 Z tch1cherin Palindromes (APIO14_palindrome) C++17
100 / 100
 437 ms 57388 KB 
#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;

vector<int> suffix_array(string S) {
  S += "$";
  int N = (int)S.size();
  vector<int> ord(N), comp(N);
  for (int i = 0; i < N; i++) {
    ord[i] = i;
    comp[i] = S[i];
  }
  sort(ord.begin(), ord.end(), [&](int i, int j) { return S[i] < S[j]; });
  vector<int> tmp(N), cnt(N + 1);
  auto Update = [&](int d) {
    int ptr = 0, x = -1, y = -1;
    for (int i : ord) {
      int j = i + d < N ? i + d : i + d - N;
      tmp[i] = comp[i] != x || comp[j] != y ? ++ptr : ptr;
      x = comp[i], y = comp[j];
    }
    comp = tmp;
  };
  auto Sort = [&](int d) {
    cnt.assign(N + 1, 0);
    for (int value : comp) {
      cnt[value]++;
    }
    partial_sum(cnt.begin(), cnt.end(), cnt.begin());
    for (int i : ord) {
      int j = i + d < N ? i + d : i + d - N;
      tmp[cnt[comp[j] - 1]++] = i;
    }
    ord = tmp;
  };
  Update(0);
  for (int d = 1; d < N; d += d) {
    Sort(d);
    Sort(0);
    Update(d);
  }
  return ord;
}

vector<int> find_lcp(string S, vector<int> ord) {
  S += "$";
  int N = (int)S.size();
  vector<int> pos(N);
  for (int i = 0; i < N; i++) {
    pos[ord[i]] = i;
  }
  vector<int> lcp(N);
  int l = 0;
  for (int i = 0; i < N; i++) {
    if (pos[i] == N - 1) {
      continue;
    }
    int j = ord[pos[i] + 1];
    while (max(i, j) + l < N && S[i + l] == S[j + l]) {
      l++;
    }
    lcp[pos[i]] = l;
    l = max(0, l - 1);
  }
  return lcp;
}

vector<int> manacher_odd(string S) {
  S += "$";
  int N = (int)S.size();
  vector<int> x(N, 1);
  int l = 0, r = 0;
  for (int i = 1; i < N; i++) {
    if (i < r) {
      x[i] = min(r - i + 1, x[l + r - i]);
    }
    while (i - x[i] >= 0 && i + x[i] < N && S[i - x[i]] == S[i + x[i]]) {
      x[i]++;
    }
    if (i + x[i] - 1 > r) {
      l = i - x[i] + 1;
      r = i + x[i] - 1;
    }
  }
  x.pop_back();
  return x;
}

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

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  string S;
  cin >> S;
  int N = (int)S.size();
  vector<int> ord = suffix_array(S);
  vector<int> lcp = find_lcp(S, ord);
  vector<int> x_odd = manacher_odd(S), x_even = manacher_even(S);
  vector<int> pos(N + 1);
  for (int i = 0; i <= N; i++) {
    pos[ord[i]] = i;
  }
  vector<int> max_pal(N + 1);
  set<int> odd, even;
  vector<vector<int>> del_odd(N), del_even(N);
  for (int i = N - 1; i >= 0; i--) {
    odd.insert(i);
    even.insert(i);
    del_odd[i - x_odd[i] + 1].push_back(i);
    del_even[i - x_even[i]].push_back(i);
    max_pal[pos[i]] = max((*odd.rbegin() - i) * 2 + 1, (*even.rbegin() - i) * 2);
    for (int v : del_odd[i]) {
      odd.erase(v);
    }
    for (int v : del_even[i]) {
      even.erase(v);
    }
  }
  vector<int> A;
  for (int i = 0; i <= N; i++) {
    A.push_back(max_pal[i]);
    A.push_back(lcp[i]);
  }
  long long ans = 1;
  vector<int> L(2 * (N + 1)), R(2 * (N + 1));
  stack<int> st;
  for (int i = 0; i < 2 * (N + 1); i++) {
    while (!st.empty() && A[i] <= A[st.top()]) {
      st.pop();
    }
    L[i] = st.empty() ? -1 : st.top();
    st.push(i);
  }
  st = stack<int>();
  for (int i = 2 * (N + 1) - 1; i >= 0; i--) {
    while (!st.empty() && A[i] <= A[st.top()]) {
      st.pop();
    }
    R[i] = st.empty() ? 2 * (N + 1) : st.top();
    if (i % 2 == 0) {
      ans = max(ans, 1LL * ((R[i] - L[i] + 1) / 2) * A[i]);
    }
    st.push(i);
  } 
  cout << ans << "\n";
}

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 600 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 408 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 452 KB Output is correct
15 Correct 0 ms 348 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 1 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 1 ms 348 KB Output is correct
21 Correct 0 ms 348 KB Output is correct
22 Correct 0 ms 348 KB Output is correct
23 Correct 0 ms 348 KB Output is correct
24 Correct 0 ms 348 KB Output is correct
25 Correct 0 ms 348 KB Output is correct
26 Correct 0 ms 348 KB Output is correct
27 Correct 0 ms 348 KB Output is correct
28 Correct 1 ms 348 KB Output is correct
29 Correct 0 ms 348 KB Output is correct
30 Correct 0 ms 348 KB Output is correct
31 Correct 0 ms 348 KB Output is correct
32 Correct 0 ms 348 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 604 KB Output is correct
2 Correct 1 ms 604 KB Output is correct
3 Correct 1 ms 600 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 604 KB Output is correct
6 Correct 1 ms 604 KB Output is correct
7 Correct 1 ms 472 KB Output is correct
8 Correct 1 ms 604 KB Output is correct
9 Correct 1 ms 604 KB Output is correct
10 Correct 1 ms 604 KB Output is correct
11 Correct 1 ms 604 KB Output is correct
12 Correct 1 ms 604 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 2140 KB Output is correct
2 Correct 5 ms 1884 KB Output is correct
3 Correct 6 ms 1884 KB Output is correct
4 Correct 6 ms 2028 KB Output is correct
5 Correct 4 ms 1884 KB Output is correct
6 Correct 5 ms 1692 KB Output is correct
7 Correct 5 ms 1884 KB Output is correct
8 Correct 5 ms 2396 KB Output is correct
9 Correct 4 ms 1884 KB Output is correct
10 Correct 5 ms 1740 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 54 ms 17736 KB Output is correct
2 Correct 54 ms 16976 KB Output is correct
3 Correct 65 ms 17236 KB Output is correct
4 Correct 66 ms 16636 KB Output is correct
5 Correct 90 ms 15280 KB Output is correct
6 Correct 80 ms 15444 KB Output is correct
7 Correct 63 ms 15440 KB Output is correct
8 Correct 56 ms 16464 KB Output is correct
9 Correct 65 ms 16208 KB Output is correct
10 Correct 96 ms 15508 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 188 ms 54468 KB Output is correct
2 Correct 167 ms 48676 KB Output is correct
3 Correct 235 ms 57388 KB Output is correct
4 Correct 197 ms 46384 KB Output is correct
5 Correct 348 ms 47048 KB Output is correct
6 Correct 232 ms 46884 KB Output is correct
7 Correct 233 ms 45252 KB Output is correct
8 Correct 191 ms 49188 KB Output is correct
9 Correct 183 ms 49208 KB Output is correct
10 Correct 437 ms 46524 KB Output is correct
11 Correct 175 ms 52160 KB Output is correct
12 Correct 180 ms 50408 KB Output is correct