Task:

 Generate a string with   N   opening brackets   [   and with   N   closing brackets   ],   in some arbitrary order. 
 Determine whether the generated 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   
   [][]         OK   
   [[][]]       OK 
   ][         NOT OK
   ][][       NOT OK
   []][[]     NOT OK



 
  gen_brackets:{"[]"@x _draw 2}
  check:{r:(-1;1)@"["=x; *(0=+/cs<'0)&(0=-1#cs:+\r)}
 
  {(x;check x)}' gen_brackets' 2*1+!10
(("[[";0)
 ("[][]";1)
 ("][][]]";0)
 ("[[][[][]";0)
 ("][]][[[[[[";0)
 ("]]][[]][]]][";0)
 ("[[[]][[[][[[][";0)
 ("[[]][[[]][]][][]";1)
 ("][[][[]]][[]]]][][";0)
 ("]][[[[]]]][][][[]]]]";0))
 