examples/rosettacode/balanced_brackets.nit

   1 #!/usr/bin/env nit
   2 #
   3 # This file is part of NIT ( http://www.nitlanguage.org ).
   4 # This program is public domain
   5
   6 # Task: Balanced brackets
   7 # SEE: <http://rosettacode.org/wiki/Balanced_brackets>
   8 module balanced_brackets
   9
  10 # Are `[` and `]` balanced?
  11 # Other characters are ignored.
  12 #
  13 #     assert is_balanced("[][[]]")
  14 #     assert is_balanced("")
  15 #     assert not is_balanced("[[]")
  16 #     assert not is_balanced("][][")
  17 fun is_balanced(s: String): Bool
  18 do
  19         var l = 0
  20         for x in s.chars do
  21                 if x == '[' then
  22                         l += 1
  23                 else if x == ']' then
  24                         l -= 1
  25                         if l < 0 then return false
  26                 end
  27         end
  28         return l == 0
  29 end
  30
  31 var n = 3
  32 if args.not_empty then n = args.first.to_i
  33
  34 for i in [0..10[ do
  35         var a = (['[', ']'] * n)
  36         a.shuffle
  37         var b = a.join("")
  38         if is_balanced(b) then print "{b} is well-balanced" else print "{b} is not well-balanced"
  39 end