编写一个递归算法，输出自然数1到n这n个元素的全排列？

Question

编写一个递归算法，输出自然数1到n这n个元素的全排列？谢谢各位了

Answer 1

class GroupSort
    {
        private List<int> _listItem = new List<int>();
        private List<int> _listGroup = new List<int>();
        private List<string> _listSortResult = new List<string>();
        private List<int> _listFlag = new List<int>();
        private int _count;
        
        public GroupSort(List<int> listGroup)
        {
            _listGroup = listGroup;
            _count = listGroup.Count;
            for(int i = 0; i < _count; ++i)
            {
                _listItem.Add(-1);
                _listFlag.Add(0);
            }
        }        public void StartSort()
        {
            Sort(0);
        }        private void Sort(int index)
        {
            if (index == _count)
            {
                string item = "";
                for (int i = 0; i < _count; i++)
                {
                    item += _listItem[i];
                }
                _listSortResult.Add(item);
            }
            else
            {
                for (int i = 0; i < _count; i++)
                {
                    if (_listFlag[i] == 0)
                    {
                        _listFlag[i] = 1;
                        _listItem[index] = _listGroup[i];
                        Sort(index + 1);
                        _listFlag[i] = 0;
                    }
                }
            }
        }        public List<string> SortResult
        {
            get
            {
                return _listSortResult;
            }
        }
    }