combination for cpp

combination.cpp

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
/* 
 combination for get m from num of numbers
 */
class combination
{
public:
    //m from num of numbers
    combination(int num,int m):init(true)
    {
        //let bits as the permutation
        bits=vector<int> (num,1);
        fill(bits.begin(),bits.begin()+m,0);
    }
    // get next result seq while true;
    bool next(vector<int> &seq)
    {
        seq.resize(0);
        if(init)
        {
            getSeq(seq);
            init =false;
            return true;
        }
        bool rval=next_permutation(bits.begin(), bits.end());
        getSeq(seq);
        return rval;
        
    }
private:
    void getSeq(vector<int> &seq)
    {
        for(int i=0;i<bits.size();i++)
        {
            if(!bits[i])seq.push_back(i+1);
        }
    }
    vector<int> bits;
    bool init;
};