最长公共子序列简单实现

int LCS(string str1, string str2)  //返回最长公共字串长度
{
    //创建矩阵
    int** martix;
    martix = new int*[str1.length()+1];
    for(int i =0; i<=str1.length(); i++)
    {
        martix[i] = new int[str2.length()+1];
    }
    //初始化矩阵
    for (int i = 0; i <= str1.length(); i++)   martix[i][0] = 0;
    for (int j = 0; j <= str2.length(); j++)   martix[0][j] = 0;
    //填充矩阵
    for (int i = 1; i <= str1.length(); i++)
    {
        for (int j = 1; j <= str2.length(); j++)
        {
            if (str1[i-1] == str2[j-1])
            {
                martix[i][j] = martix[i-1][j-1] + 1;
            }
            else
            {
                martix[i][j]=0;
            }
        }
    }
    //找到最大处即最长处
    int max(0),imax(0),jmax(0);
    for (int i = 0; i <= str1.length(); i++)
    {
        for (int j = 0; j <= str2.length(); j++)
        {
            if(martix[i][j]>max)
            {
                max = martix[i][j];
                imax = i;
                jmax = j;
            }
        }
    }
    cout<<"最长公共字串长度为："<<max<<endl;
    cout<<"最长公共字串为：";
    for(int i = max; i>0; i--)
    {
        cout<<str1[imax-i];
    }
    cout<<endl;
    for(int i =0; i<=str1.length(); i++)
    {
        delete[] martix[i];
    }
    delete[] martix;
    return max;
}