Cod sursa(job #1817894)

Utilizator cyber_ghSoltan Gheorghe cyber_gh Data 28 noiembrie 2016 17:20:26
Problema Potrivirea sirurilor Scor 40
Compilator cpp Status done
Runda Arhiva educationala Marime 2.37 kb
// C++ program for implementation of KMP pattern searching
// algorithm
#include<bits/stdc++.h>

using namespace std;

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

string pat,txt;
int k;
vector <int> a;
void computeLPSArray(string pat, int M, int *lps);

// Prints occurrences of txt[] in pat[]
void KMPSearch(string pat, string txt)
{
    int M = pat.length();
    int N = txt.length();

    // create lps[] that will hold the longest prefix suffix
    // values for pattern
    int lps[M];

    // Preprocess the pattern (calculate lps[] array)
    computeLPSArray(pat, M, lps);

    int i = 0;  // index for txt[]
    int j  = 0;  // index for pat[]
    while (i < N)
    {
        if (pat[j] == txt[i])
        {
            j++;
            i++;
        }

        if (j == M)
        {
            //fout <<i-j<<"\n";
            a.push_back(i-j);
            k++;
            j = lps[j-1];
        }

        // mismatch after j matches
        else if (i < N && pat[j] != txt[i])
        {
            // Do not match lps[0..lps[j-1]] characters,
            // they will match anyway
            if (j != 0)
                j = lps[j-1];
            else
                i = i+1;
        }
    }
}

// Fills lps[] for given patttern pat[0..M-1]
void computeLPSArray(string pat, int M, int *lps)
{
    // length of the previous longest prefix suffix
    int len = 0;

    lps[0] = 0; // lps[0] is always 0

    // the loop calculates lps[i] for i = 1 to M-1
    int i = 1;
    while (i < M)
    {
        if (pat[i] == pat[len])
        {
            len++;
            lps[i] = len;
            i++;
        }
        else // (pat[i] != pat[len])
        {
            // This is tricky. Consider the example.
            // AAACAAAA and i = 7. The idea is similar
            // to search step.
            if (len != 0)
            {
                len = lps[len-1];

                // Also, note that we do not increment
                // i here
            }
            else // if (len == 0)
            {
                lps[i] = 0;
                i++;
            }
        }
    }
}

// Driver program to test above function
int main()
{
    fin >>pat;
    fin>>txt;
    KMPSearch(pat, txt);
    fout <<a.size()<<endl;
    for(int i=0;i<a.size();i++) fout <<a[i]<<" ";
    return 0;
}