Submission #915843

#	Time	Username	Problem	Language	Result	Execution time	Memory
915843		vjudge1	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	157 ms	3540 KiB

palindromic

#include <bits/stdc++.h>
#include <cassert>

#define MAX_WORD_LENGTH 5100000

int longest_palindromic_partition(const std::string& word) {
    const int n = word.length();
    const unsigned int base = 131;
    int done_chars = 0;
    int n_chunks = 0;

    while (done_chars * 2 < n) {
        unsigned int left_hash = 0, right_hash = 0;
        unsigned int base_power = 1;

        for (int chunk_size = 1; true; chunk_size++) {
            const int l = done_chars;
            const int r = n - done_chars - chunk_size;

            if (l + chunk_size - 1 >= r) {
                return n_chunks + 1;
            }

            base_power = (chunk_size == 1) ? 1 : base_power * base;
            left_hash += static_cast<unsigned int>(word[l + chunk_size - 1]) * base_power;
            right_hash = static_cast<unsigned int>(word[r]) + right_hash * base;

            if (left_hash == right_hash && word.compare(l, chunk_size, word, r, chunk_size) == 0) {
                n_chunks += 2;
                done_chars += chunk_size;
                break;
            }
        }
    }

    return n_chunks;
}

int main() {
    int n;
    std::cin >> n;

    for (int i = 0; i < n; i++) {
        std::string word;
        std::cin >> word;
        assert(word.length() <= MAX_WORD_LENGTH);
        std::cout << longest_palindromic_partition(word) << std::endl;
    }

    return 0;
}

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