pattern-matching

问题 I have string consider my $string = 'String need to be evaluated'; in $string I'm searching evaluated or any other word. problem is their may be insertion of some tags in string eg. Str<data>ing need to be eval<data>ua<data>ted which is unexpected. In this case how could I search for the words? here is the code I tried: my $string = 'Text to be evaluated'; my $string2 = "Te<data>xt need to be eval<data2>ua<data>ted"; # patten to match $pattern = "evaluated"; @b = split('',$pattern); for my $i

问题 I would like to ask if there is an algorithm for counting the number of discrete occurencies of a substring in a string in O(n) time. 回答1: [EDIT 17/11/2013: Count the leaf nodes. Thanks Vinicius Pinto!] You can build a suffix tree on the text in linear time. Then, search for your substring in the suffix tree; when you find it, count the number of leaf nodes beneath the matching node. This is O(m + k) for a substring of length m that appears k times (add an n term for building the suffix tree)

问题 I want to match any string that has a recurring cycle. Like in this data: 3333333333333333333333333333333333333333 / 1 digit cycle(3) 1666666666666666666666666666666666666666 / 1 digit cycle(6) 1428571428571428571428571428571428571428 / 6 digit cycle(142857) 1111111111111111111111111111111111111111 / 1 digit cycle(1) 0909090909090909090909090909090909090909 / 2 digit cycle(09) 0834522467546323545411673445234655345222 / no cycle 0769230769230769230769230769230769230769 / 6 digit cycle(769230)

问题 I want to match any string that has a recurring cycle. Like in this data: 3333333333333333333333333333333333333333 / 1 digit cycle(3) 1666666666666666666666666666666666666666 / 1 digit cycle(6) 1428571428571428571428571428571428571428 / 6 digit cycle(142857) 1111111111111111111111111111111111111111 / 1 digit cycle(1) 0909090909090909090909090909090909090909 / 2 digit cycle(09) 0834522467546323545411673445234655345222 / no cycle 0769230769230769230769230769230769230769 / 6 digit cycle(769230)

问题 Scala can warn when pattern match on a sealed type is not exhaustive, however can we check that a function returns all cases when the return type is sealed? For example, consider the following ADT sealed trait Foo case object Bar extends Foo case object Qux extends Foo Then function f: Foo => String on the algebraic data type Foo def f(x: Foo): String = x match { case Bar => "bar" } raises warning match may not be exhaustive. It would fail on the following input: Qux def f(x: Foo) = x match {

问题 Please help me to understand the construction of state transition table for more than one patterns in the Aho-Corasick algorithm. Please give a simple and detailed explanation so that I could understand. I am following this paper and here is the animation for that. Thanks. 回答1: Phase 1 Creating the keyword tree : Starting at the root, follow the path labeled by chars of P i If the path ends before P i , continue it by adding new edges and ... nodes for the remaining characters of P Store

问题 I'm getting totally lost in shell programming, mainly because every site I use offers different tool to do pattern matching. So my question is what tool to use to do simple pattern matching in piped stream. context: I have named.conf file, and i need all zones names in a simple file for further processing. So I do ~$ cat named.local | grep zone and get totally lost here. My output is ~hundred or so newlines in form 'zone "domain.tld" {' and I need text in double quotes. Thanks for showing a

问题 I'm trying to understand the Haskell 2010 Report section 3.17.2 "Informal Semantics of Pattern Matching". Most of it, relating to a pattern match succeeding or failing seems straightforward, however I'm having difficulty understanding the case which is described as the pattern match "diverging". I'm semi-persuaded it means that the match algorithm does not "converge" to an answer (hence the match function never returns). But if doesn't return, then, how can it return a value, as suggested by

问题 I will use simple codes to describe my situation. For example, here are the codes: using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"\b(?!non)\w+\b"; string input = "Nonsense is not always non-functional."; foreach (Match match in Regex.Matches(input, pattern, RegexOptions.IgnoreCase)) Console.WriteLine(match.Value); } } Now, I would like to replace the "non" with a user input. Let say it's called "UserInput" and the

问题 I will use simple codes to describe my situation. For example, here are the codes: using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"\b(?!non)\w+\b"; string input = "Nonsense is not always non-functional."; foreach (Match match in Regex.Matches(input, pattern, RegexOptions.IgnoreCase)) Console.WriteLine(match.Value); } } Now, I would like to replace the "non" with a user input. Let say it's called "UserInput" and the