title: Replace Character C1 C2 C2 C1 String S
signature: replaceCharacterC1C2C2C1StringS :: String -> Char -> Char -> String
  replaceCharacterC1C2C2C1StringS s c1 c2 = 
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 :: String -> String -> Bool
  validateSolution actual expected = do
      actual == expected
  
  
  driver :: String -> Char -> Char -> String -> String
  driver s c1 c2 expected = do
      if (validateSolution (PLACEHOLDER_FN_NAME s c1 c2) expected)
          then "PASSED"
      else "FAILED"
  
  main = do
      printf "TEST-0...%s\n" (driver ("IZTSMw j") ('W') ('k') ("IZTSMw j") )
  
      printf "TEST-1...%s\n" (driver ("7288334") ('6') ('9') ("7288334") )
  
      printf "TEST-2...%s\n" (driver ("010110000") ('1') ('1') ("010110000") )
  
      printf "TEST-3...%s\n" (driver ("b gJX") ('t') ('P') ("b gJX") )
  
      printf "TEST-4...%s\n" (driver ("734") ('4') ('4') ("734") )
  
      printf "TEST-5...%s\n" (driver ("1") ('1') ('1') ("1") )
  
      printf "TEST-6...%s\n" (driver ("xCaUKdhA") ('X') ('S') ("xCaUKdhA") )
  
      printf "TEST-7...%s\n" (driver ("4370992644981") ('5') ('6') ("4370992544981") )
  
      printf "TEST-8...%s\n" (driver ("01010") ('0') ('1') ("10101") )
  
      printf "TEST-9...%s\n" (driver ("ZNIFGshaWA") ('Q') ('x') ("ZNIFGshaWA") )
  
source_py: def replace_character_c1_c2_c2_c1_string_s(s, c1, c2):
      l = len(s)
      for i in range(l):
          if (s[i] == c1):
              s = ((s[0:i] + c2) + s[(i + 1):])
          elif (s[i] == c2):
              s = ((s[0:i] + c1) + s[(i + 1):])
      return s
source_cpp: string replace_character_c1_c2_c2_c1_string_s(string s, char c1, char c2) {
    int l = s . length ( );
    for ( int i = 0;
    i < l;
    i ++ ) {
      if ( s [ i ] == c1 ) s [ i ] = c2;
      else if ( s [ i ] == c2 ) s [ i ] = c1;
    }
    return s;
  }