leetcode 77 combinations

class  {
    public List<List<Integer>> combine(int n, int k) {
        List<List<Integer>> result = new ArrayList<List<Integer>>();
        List<Integer> current = new ArrayList<Integer>();
        bfs(result, current, n , k, 1);
        return result;
    }
    public void bfs(List<List<Integer>> result, List<Integer> current, int n, int k, int c){
        if(current.size() == k){
            result.add(new ArrayList<Integer>(current));
            return ;
        }
        for(int i=c; i<=n; i++){
            current.add(i);
            bfs(result, current, n ,k, ++c);
            current.remove(current.size()-1);
            
        }
    }
}