Cod sursa(job #2723581)

Utilizator vladm98Munteanu Vlad vladm98 Data 14 martie 2021 23:17:54
Problema Potrivirea sirurilor Scor 80
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.83 kb
#include <bits/stdc++.h>

using namespace std;

unsigned int hashes[2000005]; //hash[i] = s[i] + baza * s[i + 1] + baza ^ 2 * s[i + 2] + ... + baza ^ j * s[i + j] + ...
//Tinem o pereche pentru ca vom folosi 2 baze si 2 modulo
unsigned int powers[2000005]; //powers[i] = baza ^ i
unsigned int bases = 123;

void buildHashes(string text) {
    unsigned int n = text.size();
    for (unsigned int i = n; i >= 1; --i) {
        hashes[i] = (hashes[i + 1] * bases + text[i - 1]);
    }
}

void buildPowers(string text) {
    unsigned int n = text.size();
    powers[0] = 1;
    for (unsigned int i = 1; i <= n; ++i) {
        powers[i] = powers[i - 1] * bases;
    }
}

unsigned int buildPatternHash(string pattern) {
    unsigned int n = pattern.size();
    unsigned int hash = 0;
    for (unsigned int i = n; i >= 1; --i) {
        hash = (hash * bases + pattern[i - 1]);
    }
    return hash;
}

unsigned int buildTextHash(unsigned int left, unsigned int right) {
    return (hashes[left] - hashes[right + 1] * powers[right - left + 1]);
}

bool patternMatch(unsigned int hash, unsigned int left, unsigned int right) {
    return hash == buildTextHash(left, right);
}

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

    string pattern, text;
    fin >> pattern >> text;

    buildHashes(text);
    buildPowers(text);
    unsigned int hash = buildPatternHash(pattern);
    unsigned int cnt = 0;
    for (unsigned int i = 1; i + pattern.size() - 1 <= text.size(); ++i) {
        if (patternMatch(hash, i, i + pattern.size() - 1)) {
            cnt += 1;
        }
    }
    fout << cnt << "\n";
    cnt = 0;
    for (unsigned int i = 1; i + pattern.size() - 1 <= text.size(); ++i) {
        if (cnt < 1000 and patternMatch(hash, i, i + pattern.size() - 1)) {
            cnt += 1;
            fout << i - 1 << " ";
        }
    }
    return 0;
}