Extremely fast way to clone the values of a jagged array into a second array?

Question

I am currently working on an application that is responsible for calculating random permutations of a jagged array.

Currently the bulk of the time in the applicati

Answer 1

Either of these should work for you. They both run in about the same amount of time and are both much faster than your method.

// 100 passes on a int[1000][1000] set size

// 701% faster than original (14.26%)
static int[][] CopyArrayLinq(int[][] source)
{
    return source.Select(s => s.ToArray()).ToArray();
}

// 752% faster than original (13.38%)
static int[][] CopyArrayBuiltIn(int[][] source)
{
    var len = source.Length;
    var dest = new int[len][];

    for (var x = 0; x < len; x++)
    {
        var inner = source[x];
        var ilen = inner.Length;
        var newer = new int[ilen];
        Array.Copy(inner, newer, ilen);
        dest[x] = newer;
    }

    return dest;
}