枚举可能的组合泛型实现

r囧r小猫 2022-06-18 09:36 202阅读 0赞

/// <summary>
            /// 返回集合所有可能的组合数目
            /// </summary>
            /// <param name="count">集合的数目</param>
            /// <returns>组合的数目</returns>
            static int MakeObjectCount(int count)
            {
                if (count==1)
                {
                    return 1;
                }
                else
                {
                    return count * MakeObjectCount(count-1);
                }
            }
    
            /// <summary>
            /// 返回数组中所有可能的组合集合
            /// </summary>
            /// <typeparam name="T">集合的类型</typeparam>
            /// <param name="objects">待处理的集合</param>
            /// <returns>所有可能的组合集合</returns>
         public  static List<List<T>> MakeObject<T>(T[] objects)
            {
                System.Diagnostics.Contracts.Contract.Requires(objects.Length > 0 );
    
                List<List<T>> temp = new List<List<T>>(MakeObjectCount(objects.Length));
                if (objects.Length == 1)
                {
                    var array = new List<T>();
                    array.Add(objects[0]);
                    temp.Add(array);
                }
                if (objects.Length == 2)
                {
                    var arraya = new List<T>();
                    var arrayb = new List<T>();
                    arraya.Add(objects[0]);
                    arraya.Add(objects[1]);
                    arrayb.Add(objects[1]);
                    arrayb.Add(objects[0]);
                    temp.Add(arraya);
                    temp.Add(arrayb);
                }
                else
                {
                    for (int i = 0; i < objects.Length; i++)
                    {
                        var newchar = new T[objects.Length - 1];
                        Array.Copy(objects, 1, newchar, 0, objects.Length - 1);
                        foreach (var item in MakeObject<T>(newchar))
                        {
                            item.Insert(0, objects[0]);
                            temp.Add(item);
                        }
                        T t = objects[0];
                        for (int o = 0; o < objects.Length; o++)
                        {
                            if (o == objects.Length - 1)
                            {
                                objects[o] = t;
                            }
                            else
                            {
                                objects[o] = objects[o + 1];
                            }
                        }
                    }
                }
                return temp;
            }