hardcode

finite automata hardcode.cpp

#include <iostream>
#include <string>
#include <sstream>

int main()
{
    using namespace std;
    string txt("nanonawefawefawefnaoawfnanowfawe");
    string pat("nano");
    stringstream stxt(txt);
    enum state
    {
        sempty, sn, sna, snan, snano
    };
    state s = sempty;
    char ch;
    int index(0);

    while (!stxt.eof())
    {
        stxt >> ch;
        index++;

        switch (s)
        {
        case sempty:
        {
            if (ch == 'n')
            {
                s = sn;
            }
            else
            {
                s = sempty;
            }
            break;
        }

        case sn:
        {
            if (ch == 'n')
            {
                s = sn;
            }
            else if (ch == 'a')
            {
                s = sna;
            }
            else
            {
                s = sempty;
            }
            break;
        }

        case sna:
        {
            if (ch == 'n')
            {
                s = snan;
            }
            else
            {
                s = sempty;
            }
            break;
        }

        case snan:
        {
            if (ch == 'o')
            {
                s = snano;
            }
            else if (ch == 'n')
            {
                s = sn;
            }
            else if (ch == 'a')
            {
                s = sna;
            }
            else
            {
                s = sempty;
            }
            break;
        }

        case snano:
        {
            s = sempty;
            break;
        }
        }

        if (s == snano)
        {
            cout << "find at " << index - pat.length() + 1 << endl;
        }
    }

    return 0;
}