Edit Distance (编辑距离) .NET 实现

    /// <summary>
    /// Calculate Text Edit Distance Utility Class
    /// </summary>
    public static class TextEditDistanceUtility
    {
        /// <summary>
        /// get edit distance between two string
        /// </summary>
        /// <param name="str1"></param>
        /// <param name="str2"></param>
        /// <returns></returns>
        public static int GetEditDistance(string str1, string str2)
        {
            if (str1 == str2) return 0;
            else if (String.IsNullOrEmpty(str1) && String.IsNullOrEmpty(str2)) return 0;
            else if (String.IsNullOrEmpty(str1) && !String.IsNullOrEmpty(str2)) return str2.Length;
            else if (!String.IsNullOrEmpty(str1) && String.IsNullOrEmpty(str2)) return str1.Length;
            int[,] d = new int[str1.Length + 1, str2.Length + 1];
            d.Initialize();
            int cost = 0;
            for (int i = 0; i < d.GetLength(0); i++)
            {
                d[i, 0] = i;
            }
            for (int j = 0; j < d.GetLength(1); j++)
            {
                d[0, j] = j;
            }
            for (int i = 0; i < str1.Length; i++)
            {
                for (int j = 0; j < str2.Length; j++)
                {
                    if (str1[i] == str2[j]) cost = 0;
                    else cost = 1;
                    d[i + 1, j + 1] = Math.Min(Math.Min(d[i, j + 1] + 1, d[i + 1, j] + 1), Math.Min(d[i + 1, j] + 1, d[i, j] + cost));
                }
            }
            return d[str1.Length, str2.Length];
        }
    }

Edit Distance是比较两个字符串之间需要多少次基础操作才能变成对方的操作，增加一个字符，删除一个字符，修改一个字符，均算作一次操作

比如abb和bbb，编辑距离就是1，abc变成aa，编辑距离就是2

这个算法比较多的应用就是比较两次结果之间差别有多大