C#组合函数的使用详解

如下所示：

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