recursion

问题 I am trying to reverse a sentence using recursion and print it out backwards. Right now after it prompts me to type in a sentence, it does not allow me to enter any input and ends. Is there something wrong with sc.nextLine()? How do I input a sentence as a string. private static void testNum3() { System.out.print("Type in a sentence:"); String sentence= sc.nextLine(); System.out.println(reverse(sentence)); } public static String reverse (String sentence) { if (sentence.length()== 0) return

问题 I try to transform data with recursive but I can't, I'm very newbie for recursive please help me Is it need to do with recursive or not what you guy think, Please help me (sorry for my english) This is my data const mock = [ { $: { id: '001' } }, { $: { id: '002' }, question: [{ $: { id: 'r001' }, prompt: 'some-r001', choices: [{ question: [ { $: { id: 'r001-1' }, prompt: 'some-r001-1', choices: [{ question: [{ $: { id: 'r001-1-1' }, prompt: 'some-r001-1-1', choices: [""], }] }] }, { $: { id:

问题 I have a recursive function that can produce a difficult-to-know number of expressions, each needing a new variable multiplied to it. These variables will later be removed out by calculations involving integration or residue. How can I develop these unknown number of variables? Maybe indexed? All examples I've seen on the internet are working with an a priori known object of a definite size, e.g. "item" in How can you dynamically create variables via a while loop? or Accessing the index in

问题 Given a parent, I would like to get its nodes, of level N (original dataframe is way larger) child| level| parent| 40| 1| 40| 21| 2| 40| 18| 2| 40| 37| 3| 21| 2| 3| 18| 85| 3| 21| 14| 4| 37| 58| 4| 2| 47| 4| 37| 34| 4| 85| 45| 4| 18| 32| 4| 2| 47| 4| 85| 88| 4| 85| 12| 4| 37| What I do: def get_children(x, tree, lst): for nod in tree[tree['parent'] == x]['child']: get_children(nod, tree, lst) lst.append(nod) and then I filter all nodes of level N. I would like another way because there are

问题 I have this lovely fixana function here that performs about 5 times faster than her sister ana . (i have a criterion report to back me on this) ana alg = Fix . fmap (ana alg) . alg fixana alg = fix $ \f -> Fix . fmap f . alg Can I express their cousin cata in the same fashion? cata f = f . fmap (cata f) . unFix It seems to me that I cannot, but I have been humbled by my S.O. fellows quite a few times in the past. 回答1: Actually, this has nothing to do with catamorphisms. Whenever a function is

问题 Currently I'm working on project which aims on creating watchfolder in Python that would perform certain operations. I read about watchdog library and I'm trying to implement it right now. My code is based on: Using watchdog of python to monitoring afp shared folder from linux Here is structure of folders and subfolders on which operations have to be performed. https://imgur.com/mYhZydf The main folder watchfolder contain subfolders subfolX observed recursively. At the beginning, There is

问题 The regex below captures everything up to the last balanced } . Now, what regex would be able to capture everything up to the next unbalanced } ? In other words, how can I can get ... {three {four}} five} from $str instead of just ... {three {four}} ? my $str = "one two {three {four}} five} six"; if ( $str =~ / ( .*? { (?> [^{}] | (?-1) )+ } ) /sx ) { print "$1\n"; } 回答1: So you want to match [noncurlies [block noncurlies [...]]] "}" where a block is "{" [noncurlies [block noncurlies [...]]]

问题 When I try to logout from my django project, I get the following error: "maximum recursion depth exceeded while calling a Python object" Here is the url for the logout button: url(r'^logout', 'users.views.logout', name='logout'), And here is the view: from django.shortcuts import render from deck1.models import Card from django.template import RequestContext from django.shortcuts import render_to_response from django.http import HttpResponseRedirect, HttpResponse from django.contrib.auth

问题 I have to make a breadcrumb menu which comes database. So made this function function file_list($path) { $result = array(); $q = "SELECT staticTitle,staticId,parentId FROM tbl_static_pages WHERE staticId = $path"; $run = mysql_query($q); while($row = mysql_fetch_array($run)) { if($row['parentId'] > 1) { echo $row['staticTitle']; $result = file_list($row['parentId']); return $result; // INSERTED }else { return $result; } } I have a database structure like this: id | parentId | title 3 | 1 |

问题 I have to make a breadcrumb menu which comes database. So made this function function file_list($path) { $result = array(); $q = "SELECT staticTitle,staticId,parentId FROM tbl_static_pages WHERE staticId = $path"; $run = mysql_query($q); while($row = mysql_fetch_array($run)) { if($row['parentId'] > 1) { echo $row['staticTitle']; $result = file_list($row['parentId']); return $result; // INSERTED }else { return $result; } } I have a database structure like this: id | parentId | title 3 | 1 |