title: Minimum Number Of Bracket Reversals Needed To Make An Expression Balanced
signature: int minimumNumberOfBracketReversalsNeededToMakeAnExpressionBalanced(string expr) {
test_code: #include <algorithm>
  #include <assert.h>
  #include <cstdlib>
  #include <iostream>
  #include <map>
  #include <set>
  #include <string>
  #include <tuple> 
  #include <unordered_map>
  #include <vector>
  #include <math.h>
  #include <cmath>
  #include <bits/stdc++.h>
  #include <numeric>
  #include <functional>
  
  using namespace std;
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  bool validateSolution(int actual, int expected){
      return actual == expected;
  }
  
  string driver(string expr, int expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(expr), expected)){
              return "PASSED";
          }
          return "FAILED";
      }
      catch (const std::overflow_error& exception_obj)
      {
          return typeid(exception_obj).name();
      }
      catch (const std::runtime_error& exception_obj)
      {
          return typeid(exception_obj).name();
      }
      catch (const std::exception& exception_obj)
      {
          return typeid(exception_obj).name();
      }
      catch (...)
      {
          return "UNK_ERROR";
      }
  }
  
  int main() {
      string result = "";
  
      result = driver("}{", 1); 
      cout << "TEST-" << 0 << "..."
           <<  result
           << "\n";
  
      result = driver("{{{", -1); 
      cout << "TEST-" << 1 << "..."
           <<  result
           << "\n";
  
      result = driver("{{{{", 2); 
      cout << "TEST-" << 2 << "..."
           <<  result
           << "\n";
  
      result = driver("{{{{}}", 3); 
      cout << "TEST-" << 3 << "..."
           <<  result
           << "\n";
  
      result = driver("}{{}}{{{", 4); 
      cout << "TEST-" << 4 << "..."
           <<  result
           << "\n";
  
      result = driver("{}", 1); 
      cout << "TEST-" << 5 << "..."
           <<  result
           << "\n";
  
      result = driver("", 0); 
      cout << "TEST-" << 6 << "..."
           <<  result
           << "\n";
  
      result = driver("8", -1); 
      cout << "TEST-" << 7 << "..."
           <<  result
           << "\n";
  
      result = driver("01111000", 4); 
      cout << "TEST-" << 8 << "..."
           <<  result
           << "\n";
  
      result = driver("XPkERzHcpId", -1); 
      cout << "TEST-" << 9 << "..."
           <<  result
           << "\n";
  
      return 0;
  }
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 );
  }