oj.uz

Submission #707525

# Submission time Handle Problem Language Result Execution time Memory
707525 2023-03-09T06:34:21 Z DennisTran Palindromes (APIO14_palindrome) C++17
100 / 100
 869 ms 50704 KB 
#include <vector>
#include <algorithm>
#include <iostream>
#include <set>
#include <cmath>
#include <map>
#include <random>
#include <cassert>
#include <ctime>
#include <cstdlib>
#include <queue>
#include <limits.h>
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
using namespace std;
 
int64_t binPow (int64_t x, int64_t y, int64_t MOD) {
    x %= MOD;
    int64_t res = x;
    int64_t ans = 1;
    while (y > 0) {
        if (y & 1) {
            ans *= res, ans %= MOD;
        }
        res *= res, res %= MOD;
        y /= 2;
    }
    return ans;
}
int64_t inv (int64_t x, int64_t MOD) {
    return binPow(x, MOD - 2, MOD);
}
vector<int64_t> powr = {1};
vector<int64_t> ipowr = {1};
struct Hasher {
    void resz (int mod, int base, string str) {
        int n = str.size();
        this->sz = n;
        this->MOD = mod, this->BASE = base;
        this->pref.assign(n + 1, 0);
        for (int i = 1; i <= n; i++) {
            pref[i] = (pref[i - 1] + (powr[n - i] * (str[i - 1] - 'a' + 1)) % MOD) % MOD;
            pref[i] %= MOD;
        }
    }
    int sz;
    int MOD;
    int BASE;
    vector<int64_t> pref;
    int64_t query (int l, int r) {
        if (l > sz || r > sz || l > r || l < 0 || r < 0) return -1;
        return (ipowr[sz - r - 1] * (pref[r + 1] - pref[l] + MOD) % MOD) % MOD;
    }
};
Hasher h1;
Hasher h2;
string s1;
bool isPalindrome (int l, int r) {
    if (l < 0 || r >= s1.length()) return false;
    return (h1.query(l, r) == h2.query((int)s1.length() - r - 1, (int)s1.length() - l - 1));
}
vector<int> suffix_array(string S) {
    int N = S.size();
    vector<int> sa(N), classes(N);
    for (int i = 0; i < N; i++) {
        sa[i] = N - 1 - i;
        classes[i] = S[i];
    }
    stable_sort(sa.begin(), sa.end(), [&S](int i, int j) {
        return S[i] < S[j];
    });
    for (int len = 1; len < N; len *= 2) {
        vector<int> c(classes);
        for (int i = 0; i < N; i++) {
            bool same = i && sa[i - 1] + len < N
                        && c[sa[i]] == c[sa[i - 1]]
                        && c[sa[i] + len / 2] == c[sa[i - 1] + len / 2];
            classes[sa[i]] = same ? classes[sa[i - 1]] : i;
        }
        vector<int> cnt(N), s(sa);
        for (int i = 0; i < N; i++)
            cnt[i] = i;
        for (int i = 0; i < N; i++) {
            int s1 = s[i] - len;
            if (s1 >= 0)
                sa[cnt[classes[s1]]++] = s1;
        }
    }
    return sa;
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    while (powr.size() != 1e6 + 5) {
        powr.push_back(powr.back() * 31);
        powr.back() %= (int)1e9 + 9;
    }
    ipowr.resize(powr.size());
    ipowr[0] = 1; ipowr[1] = inv(powr[1], 1e9 + 9);
    for (int i = 2; i < powr.size(); i++) {
        ipowr[i] = (ipowr[i - 1] * ipowr[1]) % ((int)1e9 + 9);
    }
    cin >> s1;
    h1.resz((int)1e9 + 9, 31, s1);
    reverse(s1.begin(), s1.end());
    h2.resz((int)1e9 + 9, 31, s1);
    reverse(s1.begin(), s1.end());
    vector<pair<int,int>> vec;
    for (int i = 0;  i < s1.size(); i++) {
        int l = 0;
        int r = s1.length();
        while (l != r) {
            //cout << l << " " << r << '\n';
            int m = (l + r + 1)/2;
            if (isPalindrome(i - m, i + m)) {
                l = m;
            } else {
                r = m - 1;
            }
        }
        vec.emplace_back(i - l, i + l);
        //[...aa...]
        if (i == s1.length() || s1[i] != s1[i + 1]) {
            continue;
        }
        l = 0;
        r = s1.length();
        while (l != r) {
            int m = (l + r + 1)/2;
            if (isPalindrome(i - m, i + m + 1)) {
                l = m;
            } else {
                r = m - 1;
            }
        }
        vec.emplace_back(i - l, i + l + 1);
        //cout << i << " " << l << '\n';
    }
    map<int64_t,pair<int,int>> myMap;
    for (auto& p: vec) {
        pair<int,int> q = p;
        while (q.first <= q.second) {
            if (myMap.count(h1.query(q.first, q.second))) {
                break;
            }
            myMap[h1.query(q.first, q.second)] = q;
            q.first++, q.second--;
        }
    }
    vector<int> v = suffix_array(s1);
    vector<int> id(v.size() + 1);
    for (int i = 0; i < v.size(); i++) {
        id[v[i]] = i;
    }
    int64_t ans = 0;
    for (auto& p: myMap) {
        int tot = h1.query(p.second.first, p.second.second);
        int l = 0;
        int r = id[p.second.first];
        while (l != r) {
            int m = (l + r)/2;
            if (h1.query(v[m], v[m] + p.second.second - p.second.first) == tot) {
                r = m;
            } else {
                l = m + 1;
            }
        }
        int L = l;
        l = id[p.second.first];
        r = s1.length() - 1;
        while (l != r) {
            int m = (l + r + 1)/2;
            if (h1.query(v[m], v[m] + p.second.second - p.second.first) == tot) {
                l = m;
            } else {
                r = m - 1;
            }
        }
        if (p.second.first - p.second.second == 2 && l - L + 1 == 10) {
            cout << p.second.first << " " << p.second.second << " " << l - L + 1 << '\n';
        }
        ans = max(ans, (int64_t)(p.second.second - p.second.first + 1) * (l - L + 1));
    }
    cout << ans;
}

Compilation message

palindrome.cpp:14: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
   14 | #pragma GCC optimization ("O3")
      | 
palindrome.cpp:15: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
   15 | #pragma GCC optimization ("unroll-loops")
      | 
palindrome.cpp: In function 'bool isPalindrome(int, int)':
palindrome.cpp:60:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     if (l < 0 || r >= s1.length()) return false;
      |                  ~~^~~~~~~~~~~~~~
palindrome.cpp: In function 'int main()':
palindrome.cpp:101:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |     for (int i = 2; i < powr.size(); i++) {
      |                     ~~^~~~~~~~~~~~~
palindrome.cpp:110:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |     for (int i = 0;  i < s1.size(); i++) {
      |                      ~~^~~~~~~~~~~
palindrome.cpp:124:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  124 |         if (i == s1.length() || s1[i] != s1[i + 1]) {
      |             ~~^~~~~~~~~~~~~~
palindrome.cpp:153:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  153 |     for (int i = 0; i < v.size(); i++) {
      |                     ~~^~~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 16068 KB Output is correct
2 Correct 24 ms 16016 KB Output is correct
3 Correct 24 ms 16052 KB Output is correct
4 Correct 24 ms 16100 KB Output is correct
5 Correct 24 ms 16092 KB Output is correct
6 Correct 24 ms 16072 KB Output is correct
7 Correct 24 ms 16064 KB Output is correct
8 Correct 23 ms 16068 KB Output is correct
9 Correct 23 ms 16068 KB Output is correct
10 Correct 23 ms 16128 KB Output is correct
11 Correct 25 ms 16180 KB Output is correct
12 Correct 24 ms 16068 KB Output is correct
13 Correct 27 ms 16032 KB Output is correct
14 Correct 25 ms 16024 KB Output is correct
15 Correct 24 ms 16068 KB Output is correct
16 Correct 23 ms 16096 KB Output is correct
17 Correct 24 ms 16116 KB Output is correct
18 Correct 23 ms 16116 KB Output is correct
19 Correct 25 ms 16028 KB Output is correct
20 Correct 24 ms 16068 KB Output is correct
21 Correct 23 ms 16052 KB Output is correct
22 Correct 24 ms 16120 KB Output is correct
23 Correct 25 ms 16068 KB Output is correct
24 Correct 24 ms 16120 KB Output is correct
25 Correct 25 ms 16228 KB Output is correct
26 Correct 24 ms 15996 KB Output is correct
27 Correct 23 ms 16068 KB Output is correct
28 Correct 23 ms 16040 KB Output is correct
29 Correct 24 ms 16068 KB Output is correct
30 Correct 25 ms 16060 KB Output is correct
31 Correct 23 ms 16100 KB Output is correct
32 Correct 23 ms 16068 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 16112 KB Output is correct
2 Correct 24 ms 16068 KB Output is correct
3 Correct 23 ms 16068 KB Output is correct
4 Correct 27 ms 16032 KB Output is correct
5 Correct 24 ms 16008 KB Output is correct
6 Correct 25 ms 16068 KB Output is correct
7 Correct 24 ms 16076 KB Output is correct
8 Correct 24 ms 16112 KB Output is correct
9 Correct 24 ms 16068 KB Output is correct
10 Correct 24 ms 16068 KB Output is correct
11 Correct 24 ms 16076 KB Output is correct
12 Correct 24 ms 16120 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 35 ms 16984 KB Output is correct
2 Correct 37 ms 17012 KB Output is correct
3 Correct 35 ms 17140 KB Output is correct
4 Correct 36 ms 17124 KB Output is correct
5 Correct 33 ms 16956 KB Output is correct
6 Correct 36 ms 17008 KB Output is correct
7 Correct 39 ms 17016 KB Output is correct
8 Correct 29 ms 16384 KB Output is correct
9 Correct 29 ms 16400 KB Output is correct
10 Correct 37 ms 16820 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 178 ms 26664 KB Output is correct
2 Correct 193 ms 26748 KB Output is correct
3 Correct 194 ms 27412 KB Output is correct
4 Correct 227 ms 27520 KB Output is correct
5 Correct 147 ms 24240 KB Output is correct
6 Correct 161 ms 25008 KB Output is correct
7 Correct 189 ms 25960 KB Output is correct
8 Correct 103 ms 20712 KB Output is correct
9 Correct 134 ms 22124 KB Output is correct
10 Correct 155 ms 24112 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 692 ms 48272 KB Output is correct
2 Correct 769 ms 48268 KB Output is correct
3 Correct 739 ms 50704 KB Output is correct
4 Correct 869 ms 50620 KB Output is correct
5 Correct 438 ms 36452 KB Output is correct
6 Correct 746 ms 45880 KB Output is correct
7 Correct 736 ms 44632 KB Output is correct
8 Correct 361 ms 30200 KB Output is correct
9 Correct 385 ms 30184 KB Output is correct
10 Correct 454 ms 37036 KB Output is correct
11 Correct 625 ms 48280 KB Output is correct
12 Correct 371 ms 32612 KB Output is correct