count number of occurence of each substring?

Question

Given a string S, I want to calculate number of substrings which occurred n times (1 <= n <= s.length()). I have done it with rolling hash, it can be done by using a suffix tree. How can it be solved using a suffix array in complexity O( n^2 ) ?

like for s = "ababaab"

n no.of string

4 1 "a" ( substring "a" is present 4 times)

3 2 "b" , "ab" (substring "b" and "ab" are present 3 times)

2 2 "ba" , "aba"

1 14 "aa" , "bab" , "baa" , "aab" , "abab" ....

Answer 1

This is not a forum to get free code, but since I was in such good mod this evning, i wrote a short example for you. But i cannot guarantee that is error free, this was written in 15 minutes without special much thoughts.

#include <iostream>
#include <cstdlib>
#include <map>

class CountStrings
{
    private:
            const std::string               text;
            std::map <std::string, int>     occurrences;

            void addString ( std::string );
            void findString ( std::string );

    public:
            CountStrings ( std::string );
            std::map <std::string, int> count ( );
};

void CountStrings::addString ( std::string text)
{
    std::map <std::string, int>::iterator iter;

    iter = ( this -> occurrences ).end ( );

    ( this -> occurrences ).insert ( iter, std::pair <std::string, int> ( text, 1 ));
}

void CountStrings::findString ( std::string text )
{
    std::map <std::string, int>::iterator iter;

    if (( iter = ( this -> occurrences ).find ( text )) != ( this -> occurrences ).end ( ))
    {
            iter -> second ++;
    }
    else
    {
            this -> addString ( text );
    }
}

CountStrings::CountStrings ( std::string _text ) : text ( _text ) { }

std::map <std::string, int> CountStrings::count ( )
{
    for ( size_t offset = 0x00; offset < (( this -> text ).length ( )); offset ++ )
    {
            for ( size_t length = 0x01; length < (( this -> text ).length ( ) - (  offset - 0x01 )); length ++ )
            {
                    std::string subtext;

                    subtext = ( this -> text ).substr ( offset, length );

                    this -> findString ( subtext );
            }
    }

    return ( this -> occurrences );
}

int main ( int argc, char **argv )
{
    std::string text = "ababaab";
    CountStrings cs ( text );
    std::map <std::string, int> result = cs.count ( );

    for ( std::map <std::string, int>::iterator iter = result.begin ( ); iter != result.end ( ); ++ iter )
    {
            std::cout << iter -> second << " " << iter -> first << std::endl;
    }

    return EXIT_SUCCESS;

}