public class LevenshteinDistance  
{  
    #region 私有变量  
    /// <summary>  
    /// 字符串1  
    /// </summary>  
    private char[] _ArrChar1;  
    /// <summary>  
    /// 字符串2  
    /// </summary>  
    private char[] _ArrChar2;  
    /// <summary>  
    /// 统计结果  
    /// </summary>  
    private Result _Result;  
    /// <summary>  
    /// 开始时间  
    /// </summary>  
    private DateTime _BeginTime;  
    /// <summary>  
    /// 结束时间  
    /// </summary>  
    private DateTime _EndTime;  
    /// <summary>  
    /// 计算次数  
    /// </summary>  
    private int _ComputeTimes;  
    /// <summary>  
    /// 算法矩阵  
    /// </summary>  
    private int[,] _Matrix;  
    /// <summary>  
    /// 矩阵列数  
    /// </summary>  
    private int _Column;  
    /// <summary>  
    /// 矩阵行数  
    /// </summary>  
    private int _Row;  
    #endregion  
    #region 属性  
    public Result ComputeResult  
    {  
        get { return _Result; }  
    }  
    #endregion  
    #region 构造函数  
    public LevenshteinDistance(string str1, string str2)  
    {  
        this.LevenshteinDistanceInit(str1,str2);  
    }  
    public LevenshteinDistance()  
    {  
    }  
    #endregion  
    #region 算法实现  
    /// <summary>  
    /// 初始化算法基本信息  
    /// </summary>  
    /// <param name="str1">字符串1</param>  
    /// <param name="str2">字符串2</param>  
    private void LevenshteinDistanceInit(string str1,string str2)  
    {  
        _ArrChar1 = str1.ToCharArray();  
        _ArrChar2 = str2.ToCharArray();  
        _Result = new Result();  
        _ComputeTimes = 0;  
        _Row = _ArrChar1.Length + 1;  
        _Column = _ArrChar2.Length + 1;  
        _Matrix = new int[_Row, _Column];  
    }  
    /// <summary>  
    /// 计算相似度  
    /// </summary>  
    public void Compute()  
    {  
        //开始时间  
        _BeginTime = DateTime.Now;  
        //初始化矩阵的第一行和第一列  
        this.InitMatrix();  
        int intCost = 0;  
        for (int i = 1; i < _Row; i++)  
        {  
            for (int j = 1; j < _Column; j++)  
            {  
                if (_ArrChar1[i - 1] == _ArrChar2[j - 1])  
                {  
                    intCost = 0;  
                }  
                else  
                {  
                    intCost = 1;  
                }  
                //关键步骤，计算当前位置值为左边+1、上面+1、左上角+intCost中的最小值   
                //循环遍历到最后_Matrix[_Row - 1, _Column - 1]即为两个字符串的距离  
                _Matrix[i, j] = this.Minimum(_Matrix[i - 1, j] + 1, _Matrix[i, j - 1] + 1, _Matrix[i - 1, j - 1] + intCost);  
                _ComputeTimes++;  
            }  
        }  
        //结束时间  
        _EndTime = DateTime.Now;  
        //相似率 移动次数小于最长的字符串长度的20%算同一题  
        int intLength = _Row > _Column ? _Row : _Column;  
        _Result.Rate = (1 - (double)_Matrix[_Row - 1, _Column - 1] / intLength).ToString().Substring(0, 6);  
        if (_Result.Rate.Length > 6)  
        {  
            _Result.Rate = _Result.Rate.Substring(0, 6);  
        }  
        _Result.UseTime = (_EndTime - _BeginTime).ToString();  
        _Result.ComputeTimes = _ComputeTimes.ToString() + " 距离为：" + _Matrix[_Row - 1, _Column - 1].ToString();  
    }  
    /// <summary>  
    /// 计算相似度  
    /// </summary>  
    /// <param name="str1">字符串1</param>  
    /// <param name="str2">字符串2</param>  
    public void Compute(string str1,string str2)  
    {  
        this.LevenshteinDistanceInit(str1, str2);  
        this.Compute();  
    }  
    /// <summary>  
    /// 初始化矩阵的第一行和第一列  
    /// </summary>  
    private void InitMatrix()  
    {  
        for (int i = 0; i < _Column; i++)  
        {  
            _Matrix[0, i] = i;  
        }  
        for (int i = 0; i < _Row; i++)  
        {  
            _Matrix[i, 0] = i;  
        }  
    }  
    /// <summary>  
    /// 取三个数中的最小值  
    /// </summary>  
    /// <param name="First"></param>  
    /// <param name="Second"></param>  
    /// <param name="Third"></param>  
    /// <returns></returns>  
    private int Minimum(int First, int Second, int Third)  
    {  
        int intMin = First;  
        if (Second < intMin)  
        {  
            intMin = Second;  
        }  
        if (Third < intMin)  
        {  
            intMin = Third;  
        }  
        return intMin;  
    }  
    #endregion  
}  
/// <summary>  
/// 计算结果  
/// </summary>  
public struct Result  
{  
    /// <summary>  
    /// 相似度  
    /// </summary>  
    public string Rate;  
    /// <summary>  
    /// 对比次数  
    /// </summary>  
    public string ComputeTimes;  
    /// <summary>  
    /// 使用时间  
    /// </summary>  
    public string UseTime;  
}  
//csharp/7290