c++ 求组合数序列 重写ＭＡＴＬＡＢ P = combs(v,m)

//m < 15, ｑｑ:997737609

void combs(std::vector<int>&v, std::vector<std::vector<int>> &P, int m)

{

//1*n

int n = v.size();

if(n == m)

{

P.push_back(v);

}

else if(m == 1)

{

P.resize(v.size());

for(int i =0; i < P.size(); i++)

{

P[i].push_back(v[i]);

}

}

else

{

P.resize(0);

if (m < n && m > 1)

{

for(int k = 0; k < n-m+1; k++)

{

std::vector<std::vector<int>> Q;

std::vector<int> vtemp(n-k-1);

std::copy(v.begin()+k+1, v.begin()+n, vtemp.begin());

combs(vtemp, Q, m-1);

std::vector<std::vector<int>> Qt(Q.size());

for(int i = 0; i < Q.size(); i++)//i rows

{

Qt[i].push_back(v[k]);

Qt[i].insert(Qt[i].end(), Q[i].begin(), Q[i].end());

}

if(P.size() == 0)

{

P = Qt;

}

else

{

P.insert(P.end(),Qt.begin(), Qt.end());

}

}

}

}

}

main()

{

 std::vector<int> v;

    v.push_back(1);

    v.push_back(2);

    v.push_back(3);

    v.push_back(4);

    v.push_back(5);

    v.push_back(6);

    v.push_back(7);

    v.push_back(8);

     std::vector<std::vector<int >> re;

   combs(v,re, 2);

}