Balanced brackets
You are encouraged to solve this task according to the task description, using any language you may know.
Problem: Generate a string with $N opening brackets ("[") and $N closing brackets ("]"), in some arbitrary order. Determine whether the string is balanced; that is, whether it consists entirely of pairs of opening/closing brackets (in that order), none of which mis-nest.
Examples:
(empty) OK [] OK ][ NOT OK [][] OK ][][ NOT OK [[][]] OK []][[] NOT OK
Perl 6
<lang perl6>sub balanced($s) {
my $l = 0;
for $s.comb {
when "]" {
--$l;
return False if $l < 0;
}
when "[" {
++$l;
}
}
return $l == 0;
}
my $N = get; my $s = (<[ ]> xx $N).pick(*).join; say "$s {balanced($s) ?? "is" !! "is not"} well-balanced"</lang>
PureBasic
<lang PureBasic>Procedure Ballanced(String$)
Protected *p.Character, cnt
*p=@String$
While *p\c
If *p\c='['
cnt+1
ElseIf *p\c=']'
cnt-1
EndIf
If cnt<0: Break: EndIf
*p+SizeOf(Character)
Wend
If cnt=0
ProcedureReturn #True
EndIf
EndProcedure</lang> Testing the procedure <lang PureBasic>Debug Ballanced("") ; #true Debug Ballanced("[]") ; #true Debug Ballanced("][") ; #false Debug Ballanced("[][]") ; #true Debug Ballanced("][][") ; #false Debug Ballanced("[[][]]") ; #true Debug Ballanced("[]][[]") ; #false</lang>