C#字符串相似度比较
编辑距离算法最先是由俄国科学家Levenshtein提出的，所以这个算法也叫做Levenshtein Distance算法。用最简单的一句话来说明这个算法就是：通过插入、删除、替换方法将字符串A变成字符串B所有的步骤就是算法中提到的编辑距离，最简 单的相似度即编辑距离的倒数。

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; 
}