title: Minimum Number Of Bracket Reversals Needed To Make An Expression Balanced
signature: minimumNumberOfBracketReversalsNeededToMakeAnExpressionBalanced :: String -> Integer
  minimumNumberOfBracketReversalsNeededToMakeAnExpressionBalanced expr = 
test_code: import Text.Printf
  import Control.Exception (catch, SomeException)
  import Data.Typeable
  import qualified Data.List as List
  import qualified Data.Map as Map
  import qualified Data.Set as Set
  
  -- SOLUTION CODE
  -- ============================================
  
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  validateSolution :: Integer -> Integer -> Bool
  validateSolution actual expected = do
      actual == expected
  
  
  driver :: String -> Integer -> String
  driver expr expected = do
      if (validateSolution (PLACEHOLDER_FN_NAME expr) expected)
          then "PASSED"
      else "FAILED"
  
  main = do
      printf "TEST-0...%s\n" (driver ("}{") (1) )
  
      printf "TEST-1...%s\n" (driver ("{{{") (-1) )
  
      printf "TEST-2...%s\n" (driver ("{{{{") (2) )
  
      printf "TEST-3...%s\n" (driver ("{{{{}}") (3) )
  
      printf "TEST-4...%s\n" (driver ("}{{}}{{{") (4) )
  
      printf "TEST-5...%s\n" (driver ("{}") (1) )
  
      printf "TEST-6...%s\n" (driver ("") (0) )
  
      printf "TEST-7...%s\n" (driver ("8") (-1) )
  
      printf "TEST-8...%s\n" (driver ("01111000") (4) )
  
      printf "TEST-9...%s\n" (driver ("XPkERzHcpId") (-1) )
  
source_py: def minimum_number_of_bracket_reversals_needed_to_make_an_expression_balanced(expr):
      lenn = len(expr)
      if (lenn % 2):
          return (- 1)
      s = []
      for i in range(lenn):
          if ((expr[i] == '') and len(s)):
              if (s[0] == ''):
                  s.pop(0)
              else:
                  s.insert(0, expr[i])
          else:
              s.insert(0, expr[i])
      red_len = len(s)
      n = 0
      while (len(s) and (s[0] == '')):
          s.pop(0)
          n += 1
      return ((red_len // 2) + (n % 2))
source_cpp: int minimum_number_of_bracket_reversals_needed_to_make_an_expression_balanced(string expr) {
    int len = expr . length ( );
    if ( len % 2 ) return - 1;
    stack < char > s;
    for ( int i = 0;
    i < len;
    i ++ ) {
      if ( expr [ i ] == '}' && ! s . empty ( ) ) {
        if ( s . top ( ) == '{' ) s . pop ( );
        else s . push ( expr [ i ] );
      }
      else s . push ( expr [ i ] );
    }
    int red_len = s . size ( );
    int n = 0;
    while ( ! s . empty ( ) && s . top ( ) == '{' ) {
      s . pop ( );
      n ++;
    }
    return ( red_len / 2 + n % 2 );
  }