Use: (define (reverse1 l) (if (null? l) nil (append (reverse1 (cdr l)) (list (car l))) ) ) Explanation: Rules: If the list is empty, then the reverse list is also empty Else behind the reverse tail of the list, add the first element of the list Look at this code this way: reverse1 is name … Read more
In order to pick five characters from a string recursively, follow a simple algorithm: Your method should get a portion filled in so far, and the first position in the five-character permutation that needs a character If the first position that needs a character is above five, you are done; print the combination that you … Read more
I don’t know a regex engine that can capture a quantifier. However, it is possible with PCRE or Perl to use some tricks to check if you have the same number of characters. With your example: @@@@ “Star Wars” ==== “1977” —- “Science Fiction” //// “George Lucas” you can check if @ = – / … Read more
You almost certainly want to declare next_command as a pointer. Having a structure that contains itself isn’t possible (in any language). I think this is what you want: class EthercatDatagram(Structure): pass EthercatDatagram._fields_ = [ (“header”, EthercatDatagramHeader), (“packet_data_length”, c_int), (“packet_data”, c_char_p), (“work_count”, c_ushort), (“next_command”, POINTER(EthercatDatagram))]
I think this should get you started. I created a MyObject class to mimic your object . public class MyObject { public int Id; public int ParentId; public string Name; } Here is a method to recursivley add tree view nodes based on the list. protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { … Read more
You intend to execute two expressions inside the consequent part of the if, but if only allows one expression in the consequent and one in the alternative. Surrounding both expressions between parenthesis (as you did) won’t work: the resulting expression will be evaluated as a function application of the first expression with the second expression … Read more
You’re about 99% there. Think of your base case and your recursive step – when you hit 0, what do you want to do? When you’re still working your way down from n, what do you want to happen? If you reverse the order in which you print the value, you’ll reach your desired result. … Read more
It’s not an exception per se, but if you just want to be able to limit your stack usage to a fixed amount, you could do something like this: #include <stdio.h> // These will be set at the top of main() static char * _topOfStack; static int _maxAllowedStackUsage; int GetCurrentStackSize() { char localVar; int curStackSize … Read more
public class Comment { public int Id { get; set; } public int ParentId { get; set; } public string Text { get; set; } public List<Comment> Children { get; set; } } class Program { static void Main() { List<Comment> categories = new List<Comment>() { new Comment () { Id = 1, Text = … Read more
Assuming that you use Java 8, you could do that with the Stream API thanks to the method flatMap(Function<? super T,? extends Stream<? extends R>> mapper) as next: // 1. Convert the Set as a Stream of List<Map<String, List<Object>>> // 2. Extract the elements of the lists to get a Stream of Map<String, List<Object>> // … Read more