using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication1 {     class Class1     {         static string[] str = { "A", "B", "C", "D", "E" };         static void Main()         {             Dictionary<string, int> dic = new Dictionary<string, int>();             //将数组元素添加到dic             for (int i = 0; i < str.Length; i++)             {                 dic.Add(str[i], i);             }             GetDic(dic);             Console.ReadLine();         }         static void GetDic(Dictionary<string, int> dd)         {             Dictionary<string, int> dic = new Dictionary<string, int>();             //主要是抓住AB,AC,AD,AE,然后就是开始从 BC，BD这样的原理用dd中的键与数组的中对应索引比dd中的value大进行组合             foreach (KeyValuePair<string, int> kk in dd)             {                 for (int i = kk.Value + 1; i < str.Length; i++)                 {                     Console.WriteLine(kk.Key + str[i]);                     dic.Add(kk.Key + str[i], i);                 }             }             //递归             if (dic.Count > 0) GetDic(dic);         }     } } 结果 AB AC AD AE BC BD BE CD CE DE ABC ABD ABE ACD ACE ADE BCD BCE BDE CDE ABCD ABCE ABDE ACDE BCDE ABCDE