php 两个数组能组合多少种可能?

using System;
using System.Linq;
using System.Collections.Generic;

public class Test
{
    public static void Main()
    {
        string[] a = { "zeng", "he", "b" };
        string[] b = { "ceng", "huo", "b" };
        string[] c = { "ceng", "hu", "b" };
        string[][] d = { a, b, c };
        List<string> r = new List<string>() { "" };
        List<string> r1 = new List<string>() { };
        for (int i = 0; i < d.Count(); i++)
        {
            foreach (string s in r)
            {
                foreach (string[] s1 in d)
                {
                    r1.Add(s + s1[i]);
                }
            }
            r = r1.ToList();
            r1.Clear();
        }
        foreach (string s in r.Distinct())
        {
            Console.WriteLine(s);
        }
    }
}
zengheb
zenghuob
zenghub
cengheb
cenghuob
cenghub