Kombinationer [C++]

#include <iostream.h>
#include <string.h>

char	*pattern;
char	*output;
int	pattern_length;
int	max_length;
int	counter	= 1;

// # Retunerar false om längden >= max_length #
bool next()
{
	int i		= 0;
	int n		= counter;
	char *foo	= new char [max_length];

	// Donar
	while (n != 0)
	{
		if (n / pattern_length != 0)
			foo[i] = pattern[n % pattern_length];
		else
			foo[i] = pattern[n % pattern_length - 1];

		n /= pattern_length;

		i++;

		if (i >= max_length)
		{
			delete [] foo;
			return false;
		}
	}

	for (n = 0; n < i; n++)
		output[i - n - 1] = foo[n];

	output[i] = NULL;

	delete [] foo;

	counter++;

	return true;
}

// # Återställer #
void reset()
{
	counter = 1;
}


// # En test main #
int main()
{
	pattern = new char [128];
	output	= new char [128];
	
	strcpy(pattern,"abcdefgh");
	
	pattern_length	= 4;
	max_length	= 5;

	for (int i = 0; i < 20; i++)
	{
		if (next())
			cout << output << endl;
		else
			break;
	}

	delete [] pattern;
	delete [] output;

	return 0;
}

a
b
c
aa
ab
ac
ad
ba
bb
bc
bd
ca
cb
cc
cd
aaa
aab
aac
aad
aba

#include "stdafx.h"
#include <atlstr.h>

using namespace std;

void getPattern(int nLevel, CString strResult, CString* pPattern)
{
    --nLevel;
    if (nLevel >= 0)
        for (int i = 0; i < pPattern->GetLength(); i++)
            getPattern(nLevel, strResult + pPattern->Mid(i, 1), pPattern); 
    else
        printf("%s\n", strResult);
    return;
}

int _tmain(int argc, _TCHAR* argv[])
{
    CString strPattern = "ab";
    int     nMaxLength = 3;

    for (int i = 1; i <= nMaxLength; i++)
        getPattern(i,  "", &strPattern);

    return 0;
}