数组中子数组的kmp查找算法

数组的扩展方法，创建一个静态类，将该方法加入到静态类中，在使用时，添加对该静态类名称空间的引用，就可使用该扩展方法。

public static int FindIndexOf<T>(this T[] source, T[] pattern, int start)
        {
            if(source==null||pattern==null)
            return -1;
            if (pattern.Length > source.Length - start)
            {
                //If the compare string is shorter than the test area it is not a match.
                return -1;
            }
            var next = new int[pattern.Length];
            for (int k = 0; k < next.Length; k++)
            {
                next[k] = -1;
            }
            int i = start, j = 0, sLen = source.Length,plen=pattern.Length;

            BuildTable(pattern, ref next);

            while (i < sLen&&j<plen)
            {
                if (j == -1 || source[i].Equals(pattern[j]))
                {
                    i++;
                    j++;
                }
                else
                {
                    j = next[j];
                }

                if (j >= plen)
                {
                    return i - plen;
                }
            }
            return -1;
        }
        static void BuildTable<T>(T[] pattern, ref int[] next)
        {

            int j = 0, k = -1;
            next[0] = -1;
            while (j < pattern.Length - 1)
            {
                if (-1 == k || pattern[j].Equals( pattern[k]))
                {
                    j++;
                    k++;
                    next[j] = k;
                }
                else
                {
                    k = next[k];
                }
            }
        }

 

示例：

string[] source=new string[]{"aa","bb","cc","dd"};
string[] pattern=new string[]{"bb","cc"};
int index=source.FindIndexOf(pattern,0);