using System;namespace ConsoleApplication10{    class Program    {        static void Main(string[] args)        {            Console.WriteLine(index("cbbcbcbb","acbc"));            Console.WriteLine(index("cbbcbcbb","bcb"));            Console.ReadLine();        }        static int index(string s ,string t)        {            int i = 0, j = 0, k;            while (i<s.Length&&j<t.Length)            {                if (s[i]==t[j])                {//如果相等继续匹配                    i++;                    j++;                 }                else                {//不相等时回溯                     i = i - j + 1;                    j = 0;                }            }            if (j>=t.Length)            {//匹配成功                k = i - t.Length;            }            else            {                k=-1;            }            return k;        }    }}