LeetPolvo

leetpolvo.rb

# ruby 3+
# gem install test-unit
require 'test/unit/assertions'
include Test::Unit::Assertions

def balanced?(input)
  delimiters = { 
    "(" => ")", 
    "{" => "}", 
    "[" => "]" 
  }

  stack = []

  for char in input.chars
    case char
    when *delimiters.keys
      stack.push(char)
    when *delimiters.values
      return false if delimiters[stack.pop] != char
    end
  end

  stack.size == 0
end

assert balanced?("abc")
assert balanced?("(abc)")
assert balanced?("(ab(c))")
assert balanced?("(abc)d")
assert balanced?("(abc[%def])")
assert balanced?("$(abc[de]fg{hi}jk)%//")

refute balanced?("(abc")
refute balanced?("(ab(c)")
refute balanced?("abcd]")
refute balanced?("(abc]d")
refute balanced?("(({abc})")
refute balanced?("(ab[cd)ef]")
refute balanced?("{ab(cd}ef)")