正好这几天在关注这块，看到了别人的一个java实现(http://www.360doc.com/content/090201/10/96202_2430993.html)，边改成了c#版本的，使用了一下，还可以，符合我的要求。

using System;
using System.Collections.Generic;
using System.Text;

namespace test
{
    public class Similarity
    {
        private int min(int one, int two, int three)
        {
            int min = one;
            if (two < min)
            {
                min = two;
            }
            if (three < min)
            {
                min = three;
            }
            return min;
        }

        public int levDistance(String str1, String str2)
        {
            int n = str1.Length;
            int m = str2.Length;
            int i;    //遍历str1的
            int j;    //遍历str2的
            char ch1;    //str1的
            char ch2;    //str2的
            int temp;    //记录相同字符,在某个矩阵位置值的增量,不是0就是1
            if (n == 0)
            {
                return m;
            }
            if (m == 0)
            {
                return n;
            }
            int[][] d = new int[n + 1][]; //矩阵

            for (i = 0; i <= n; i++)
            {    //初始化第一列
                d[i] = new int[m + 1];
                d[i][0] = i;
            }
            for (j = 0; j <= m; j++)
            {    //初始化第一行
                d[0][j] = j;
            }
            for (i = 1; i <= n; i++)
            {    //遍历str1
                ch1 = str1[i - 1];
                //去匹配str2
                for (j = 1; j <= m; j++)
                {
                    ch2 = str2[j - 1];
                    if (ch1 == ch2)
                    {
                        temp = 0;
                    }
                    else
                    {
                        temp = 1;
                    }
                    //左边+1,上边+1, 左上角+temp取最小
                    d[i][j] = min(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + temp);
                }
            }
            return d[n][m];
        }
        public double similarity(String str1, String str2)
        {
            int ld = levDistance(str1, str2);
            return 1 - (double)ld / Math.Max(str1.Length, str2.Length);
        }

        static void Main(string[] args)
        {
            Similarity s = new Similarity();
            String str11 = "expert";
            String str22 = "except";
            Console.WriteLine("ld=" + s.levDistance(str11, str22));
            Console.WriteLine("sim=" + s.similarity(str11, str22));
        }
    }
}