Permutation Example

#include "bits/stdc++.h"
using namespace std;

void show(const vector<int> & b)
{
  for(int i=0; i<b.size(); ++i) cout << b[i];
  cout << endl;
}

int main() {
  int n, k, i=0;
  cin >> n >> k;
  vector<int> a(n, 0);
  for(i = n-k; i<n; ++i) a[i] = 1;
  do
  {
    show(a);
  } while(next_permutation(a.begin(), a.end()));
}