[c++] Creating all possible k combinations of n items in C++

It can also be done using backtracking by maintaining a visited array.

void foo(vector<vector<int> > &s,vector<int> &data,int go,int k,vector<int> &vis,int tot)
{

    vis[go]=1;
    data.push_back(go);
    if(data.size()==k)
    {
        s.push_back(data);
        vis[go]=0;
    data.pop_back();
        return;
    }

    for(int i=go+1;i<=tot;++i)
    {
       if(!vis[i])
       {
           foo(s,data,i,k,vis,tot);
       }
    }
    vis[go]=0;
    data.pop_back();
}


vector<vector<int> > Solution::combine(int n, int k) {
   vector<int> data;
   vector<int> vis(n+1,0);
   vector<vector<int> > sol;
   for(int i=1;i<=n;++i)
   {
       for(int i=1;i<=n;++i) vis[i]=0;
   foo(sol,data,i,k,vis,n);
   }
   return sol;

}

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