产生一个数组的全排列,非冗余 C++实现

 finds all the permutaitons of n elements, repeated elements are allowed and do not create redundant permutations.

蛋白质组学Ms-TopDown源代码auxfun.cpp中一个函数,看了很久没有注释,有点晕,但是以后可以直接拿来使用.

产生原始数组元素的全排列,但是要求是非冗余的,也就是说原始数组可以有重复的元素,比如{2,2,2}这个数组,只有一种排列,2这个元素必须按相同处理,只是个数是3

void generate_all_permutations(const vector<int>& org_vector, 
                               vector< vector<int> >& permutations)
{
    unsigned int i;
    vector<int> counts, symbols;
    permutations.clear();

    if (org_vector.size() == 0)
        return;

    counts.clear();
    symbols.clear();

    // create vector with symbols and their counts
    symbols.push_back(org_vector[0]);
    counts.push_back(1);

    for (i=1; i<org_vector.size(); i++)
    {
        unsigned int j;
        for (j=0; j<counts.size(); j++)
        {
            if (org_vector[i] == symbols[j])
            {
                counts[j]++;
                break;
            }
        }

        if (j == counts.size())
        {
            symbols.push_back(org_vector[i]);
            counts.push_back(1);
        }
    }

    vector<int> next_sym_idx,perm;
    int n = org_vector.size(); // total number of elements
    int k = counts.size(); // total number of element types
    next_sym_idx.resize(n,0);
    perm.resize(n,-1);
    int d=0;

    while (1)
    {
        while (next_sym_idx[d]<k && counts[next_sym_idx[d]] == 0)
            next_sym_idx[d]++;

        if (next_sym_idx[0]==k)
            break;

        if (next_sym_idx[d] >= k)
        {
            next_sym_idx[d]=0;
            d--;
            counts[next_sym_idx[d]]++;
            next_sym_idx[d]++;
            continue;
        }

        // add symbol
        perm[d]=symbols[next_sym_idx[d]];
        counts[next_sym_idx[d]]--;
        d++;

        if (d == n)
        {
            permutations.push_back(perm);
    //        int k;
    //        for (k=0; k<perm.size(); k++)
    //            cout << perm[k] << " ";
    //        cout << endl;

            d--;
            counts[next_sym_idx[d]]++;
            next_sym_idx[d]++;
        }
    }
}