נתונות הפעולות What, Why ו-WhyHelp:

public static bool What(string s, char c, int k)
{
    if(k == 0 && s.Length == 0) return true;
    if(s.Length == 0) return false;
    if(k < 0 ) return false;
    if(s[0] == c) return What(s.Substring(1),c, k-1);
    return What(s.Substring(1),c, k);
}
public static bool Why(char[] arr, string s)
{
    return WhyHelp(arr, s, 0);
}
public static bool WhyHelp(char[] arr, string s, int k)
{
    if(k == arr.Length) return true;
    if(!What(s, arr[k], k+1)) return false;
    return WhyHelp(arr, s, k+1);
}