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Submission #229784

# Submission time Handle Problem Language Result Execution time Memory
229784 2020-05-06T12:59:35 Z tatyam Palindromes (APIO14_palindrome) C++17
100 / 100
 325 ms 23504 KB 
#include <bits/stdc++.h>
using namespace std;
using ull = uint64_t;
using u128 = __uint128_t;
using pii = pair<int, int>;
template<class T, class U> bool chmax(T& a, const U& b){ if(a < b){ a = b; return 1; } return 0; }

constexpr ull mod = 0x1fffffffffffffff, base = 257;
struct RollingHash{
    const int n;
    vector<ull> data, power;
    static constexpr ull mul(ull a, ull b){
        u128 c = (u128)a * b;
        ull ans = ull(c >> 61) + ull(c & mod);
        if(ans >= mod) ans -= mod;
        return ans;
    }
    RollingHash(const string& s): n(s.size()), data(n + 1), power(n + 1){
        power[0] = 1;
        data[0] = 1;
        for(int i = 0; i < n; i++){
            power[i + 1] = mul(power[i], base);
            data[i + 1] = mul(data[i], base) + s[i];
            if(data[i + 1] >= mod) data[i + 1] -= mod;
        }
    }
    ull get(int l, int r){
        const ull L = mul(data[l], power[r - l]);
        const ull R = data[r];
        return R - L + (R < L ? mod : 0);
    }
};
vector<int> manacher(const string& S){
    string s = {S[0]};
    for(int i = 1; i < S.size(); i++){
        s += '$';
        s += S[i];
    }
    const int n = s.size();
    vector a(n, 0);
    for(int i = 0, j = 0; i < n; ){
        while(i - j >= 0 && i + j < n && s[i - j] == s[i + j]) j++;
        a[i] = j;
        int k = 1;
        for(; i - k >= 0 && i + k < n && k + a[i - k] < j; k++) a[i + k] = a[i - k];
        i += k;
        j -= k;
    }
    return a;
}
int main(){
    string s;
    cin >> s;
    RollingHash rh(s);
    auto a = manacher(s);
    auto comp = [](pii a, pii b){ return a.second - a.first < b.second - b.first; };
    priority_queue<pii, vector<pii>, decltype(comp)> q(comp);
    unordered_map<ull, ull> cnt;
    for(int i = 0; i < a.size(); i++){
        int l = (i - a[i] + 2) / 2, r = (i + a[i] + 1) / 2;
        if(l >= r) continue;
        auto [iter, changed] = cnt.try_emplace(rh.get(l, r), 0);
        if(changed) q.emplace(l, r);
        iter->second++;
    }
    ull ans = 0;
    while(q.size()){
        auto [l, r] = q.top();
        q.pop();
        ull a = cnt[rh.get(l, r)];
        chmax(ans, a * (r - l));
        l++; r--;
        if(l < r){
            auto [iter, changed] = cnt.try_emplace(rh.get(l, r), 0);
            if(changed) q.emplace(l, r);
            iter->second += a;
        }
    }
    cout << ans << endl;
}

Compilation message

palindrome.cpp: In function 'std::vector<int> manacher(const string&)':
palindrome.cpp:35:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 1; i < S.size(); i++){
                    ~~^~~~~~~~~~
palindrome.cpp: In function 'int main()':
palindrome.cpp:59:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < a.size(); i++){
                    ~~^~~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 256 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 4 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 5 ms 256 KB Output is correct
10 Correct 5 ms 384 KB Output is correct
11 Correct 4 ms 256 KB Output is correct
12 Correct 5 ms 384 KB Output is correct
13 Correct 5 ms 256 KB Output is correct
14 Correct 5 ms 256 KB Output is correct
15 Correct 5 ms 256 KB Output is correct
16 Correct 5 ms 384 KB Output is correct
17 Correct 5 ms 256 KB Output is correct
18 Correct 4 ms 256 KB Output is correct
19 Correct 5 ms 384 KB Output is correct
20 Correct 5 ms 384 KB Output is correct
21 Correct 4 ms 384 KB Output is correct
22 Correct 5 ms 384 KB Output is correct
23 Correct 5 ms 256 KB Output is correct
24 Correct 5 ms 384 KB Output is correct
25 Correct 5 ms 256 KB Output is correct
26 Correct 4 ms 384 KB Output is correct
27 Correct 4 ms 256 KB Output is correct
28 Correct 4 ms 256 KB Output is correct
29 Correct 5 ms 256 KB Output is correct
30 Correct 4 ms 256 KB Output is correct
31 Correct 5 ms 288 KB Output is correct
32 Correct 4 ms 256 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 5 ms 384 KB Output is correct
9 Correct 5 ms 384 KB Output is correct
10 Correct 5 ms 384 KB Output is correct
11 Correct 5 ms 384 KB Output is correct
12 Correct 5 ms 384 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 1204 KB Output is correct
2 Correct 10 ms 1024 KB Output is correct
3 Correct 10 ms 1024 KB Output is correct
4 Correct 10 ms 1024 KB Output is correct
5 Correct 8 ms 1024 KB Output is correct
6 Correct 9 ms 1024 KB Output is correct
7 Correct 9 ms 1024 KB Output is correct
8 Correct 6 ms 640 KB Output is correct
9 Correct 6 ms 640 KB Output is correct
10 Correct 8 ms 896 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 65 ms 7564 KB Output is correct
2 Correct 82 ms 7308 KB Output is correct
3 Correct 70 ms 7516 KB Output is correct
4 Correct 75 ms 7480 KB Output is correct
5 Correct 45 ms 6812 KB Output is correct
6 Correct 47 ms 6036 KB Output is correct
7 Correct 57 ms 6800 KB Output is correct
8 Correct 17 ms 3200 KB Output is correct
9 Correct 26 ms 3900 KB Output is correct
10 Correct 44 ms 6292 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 250 ms 21788 KB Output is correct
2 Correct 290 ms 21972 KB Output is correct
3 Correct 325 ms 23504 KB Output is correct
4 Correct 313 ms 23500 KB Output is correct
5 Correct 169 ms 20560 KB Output is correct
6 Correct 246 ms 21156 KB Output is correct
7 Correct 256 ms 20992 KB Output is correct
8 Correct 42 ms 8408 KB Output is correct
9 Correct 43 ms 8408 KB Output is correct
10 Correct 146 ms 19716 KB Output is correct
11 Correct 244 ms 21012 KB Output is correct
12 Correct 56 ms 9356 KB Output is correct