import std.traits : isSomeString;

​

ulong levenshteinEditDistance(T)(in ref T a, in ref T b) if (isSomeString!T) {

    import std.array : uninitializedArray;

​

    auto matrix = uninitializedArray!(ulong[][])(a.length + 1, b.length + 1);

    foreach (i; 0 .. a.length + 1)

        matrix[i][0] = i;

​

    foreach (j; 0 .. b.length + 1)

        matrix[0][j] = j;

​

    import std.algorithm : min;

​

    for (int i = 1; i < a.length + 1; ++i)

        for (int j = 1; j < b.length + 1; ++j) {

            const ulong substitutionCost = a[i - 1] == b[j - 1] ? 0 : 1;

            matrix[i][j] = min(matrix[i - 1][j - 1] + substitutionCost,

                    matrix[i][j - 1] + 1, matrix[i - 1][j] + 1);

        }

​

    return matrix[a.length][b.length];

}

​

void main(string[] args) {

    import std.datetime.stopwatch : StopWatch, AutoStart;

​

    auto sw = StopWatch(AutoStart.yes);

    const auto t0 = sw.peek();

    const auto result = levenshteinEditDistance(args[1], args[2]);

    const auto t1 = sw.peek();

    sw.stop();

​

    import std.stdio : writefln;

​

    writefln("%s (%s microseconds).", result, (t1 - t0).total!"usecs");

}

​