balance_parenthesis.py

#!/usr/bin/env python

import re
import string

def process_string_re(line):
  """Removes alphanumeric characters using regular expressions."""
  return re.sub(r'[a-z0-9]', '', line)

def process_string(line):
  """Removes alphanumeric characters without regular expressions."""
  s = line
  for char in range(0, 9) + string.lowercase[:26]:
    s = s.replace(char, "")
  return s

def check_balance(line):
  """Checks if a line is balanced."""
  parenthesis = ["{}", "[]", "()"]
  s = process_string_re(line)
  for match in parenthesis:
    s = s.replace(match, "")

  return len(s) == 0

input_data = open('./input.txt', 'r').read().split("\n")
for line in input_data:
  if len(line) == 0: continue
  if check_balance(line):
    print "balanced"
  else:
    print "not balanced"

File.readlines("input.txt").each { |line| puts line.chomp.gsub(/[a-z0-9]/, "").gsub("{}", "").gsub("[]", "").gsub("()", "").length == 0 ? "balanced" : "not balanced" }