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Cod sursa(job #2725926)

Utilizator preda.andreiPreda Andrei preda.andrei Data 19 martie 2021 21:04:40
Problema Potrivirea sirurilor Scor 78
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.04 kb
#include <cstdint>
#include <fstream>
#include <string>
#include <vector>

using namespace std;

class Result {
public:
    void AddMatch(int pos);

    friend ostream& operator<<(ostream& os, const Result& res);

private:
    vector<int> matches_;
    int match_count_ = 0;
};

void Result::AddMatch(int pos) {
    if (matches_.size() < 1000) {
        matches_.push_back(pos);
    }
    match_count_ += 1;
}

ostream& operator<<(ostream& os, const Result& res) {
    os << res.match_count_ << "\n";
    for (const auto& pos : res.matches_) {
        os << pos << " ";
    }
    os << "\n";
    return os;
}

constexpr int64_t kBase = 26;
constexpr int64_t kMod = 1 << 25;

int64_t Power(int64_t base, int64_t exp) {
    if (exp == 0) {
        return 1;
    } else if (exp == 1) {
        return base % kMod;
    }

    if (exp % 2 == 1) {
        return (base % kMod * Power(base, exp - 1)) % kMod;
    }

    auto root = Power(base, exp / 2);
    return (root * root) % kMod;
}

int64_t Hash(const string& str) {
    int64_t hash = 0;
    for (const auto& ch : str) {
        hash = (hash * kBase + (ch - 'A')) % kMod;
    }
    return hash;
}

Result Solve(const string& needle, const string& haystack) {
    int64_t needle_hash = Hash(needle);
    int64_t curr_hash = Hash(haystack.substr(0, needle.size() - 1));

    int64_t pow = Power(kBase, needle.size() - 1);
    Result res;

    for (size_t i = needle.size() - 1; i < haystack.size(); i += 1) {
        curr_hash = (curr_hash * kBase % kMod + (haystack[i] - 'A')) % kMod;

        auto l = i + 1 - needle.size();
        auto same = curr_hash == needle_hash
                 && needle == haystack.substr(l, needle.size());
        if (same) {
            res.AddMatch(l);
        }

        curr_hash = (curr_hash - pow * (haystack[l] - 'A') % kMod) % kMod;
    }
    return res;
}

int main() {
    ifstream fin("strmatch.in");
    ofstream fout("strmatch.out");

    string needle, haystack;
    getline(fin, needle);
    getline(fin, haystack);

    auto res = Solve(needle, haystack);
    fout << res << "\n";

    return 0;
}