Damerau–Levenshtein distance (Edit Distance with Transposition) c implementation

Question

I implemented the Damerau–Levenshtein distance in c++ but it does not give correct o/p for the input (pantera,aorta) the correct o/p is 4 but my code gives 5.....

Answer 1

Here is my C++ version of this algorithm:

int damerau_levenshtein_distance(std::string p_string1, std::string p_string2)
{
    int l_string_length1 = p_string1.length();
    int l_string_length2 = p_string2.length();
    int d[l_string_length1+1][l_string_length2+1];

    int i;
    int j;
    int l_cost;

    for (i = 0;i <= l_string_length1;i++)
    {
        d[i][0] = i;
    }
    for(j = 0; j<= l_string_length2; j++)
    {
        d[0][j] = j;
    }
    for (i = 1;i <= l_string_length1;i++)
    {
        for(j = 1; j<= l_string_length2; j++)
        {
            if( p_string1[i-1] == p_string2[j-1] )
            {
                l_cost = 0;
            }
            else
            {
                l_cost = 1;
            }
            d[i][j] = std::min(
            d[i-1][j] + 1,                  // delete
            std::min(d[i][j-1] + 1,         // insert
            d[i-1][j-1] + l_cost)           // substitution
            );
            if( (i > 1) && 
            (j > 1) && 
            (p_string1[i-1] == p_string2[j-2]) && 
            (p_string1[i-2] == p_string2[j-1])
            ) 
            {
            d[i][j] = std::min(
            d[i][j],
             d[i-2][j-2] + l_cost   // transposition
            );
            }
        }
    }
    return d[l_string_length1][l_string_length2];
}