title: Lexicographically Next String
signature: class Solution {
  
      public string LexicographicallyNextString(string s) {
test_code: using System;
  using System.Numerics;
  using System.Diagnostics;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Security.Cryptography;
  using System.Web.UI;
  using System.Web.Script.Serialization;
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  namespace EvaluatePrediction {
      class TestRunner {
          public bool ValidateSolution(string actual, string expected){
              return new JavaScriptSerializer().Serialize(actual) == new JavaScriptSerializer().Serialize(expected);
          }
  
          public string driver(string s, string expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                string pred_result = solution_cls.PLACEHOLDER_FN_NAME(s); 
                if (ValidateSolution(
                      pred_result,
                      expected)){
                  return "PASSED";
                }
                return "FAILED";
              } 
              catch (Exception exception_obj)
              {
                return exception_obj.GetType().FullName;
              }
          }
          static void Main(string[] args) {
              TestRunner runner = new TestRunner();
              String result;
              result = runner.driver(
                  "amKIRzPiqLTIy", 
                  "amKIRzPiqLTIz"
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  "68", 
                  "69"
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  "100", 
                  "110"
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );result = runner.driver(
                  "f", 
                  "g"
              );
              Console.WriteLine(string.Format(
                  "TEST-3...{0}",
                  result)
              );result = runner.driver(
                  "802205375", 
                  "802206375"
              );
              Console.WriteLine(string.Format(
                  "TEST-4...{0}",
                  result)
              );result = runner.driver(
                  "0111", 
                  "0211"
              );
              Console.WriteLine(string.Format(
                  "TEST-5...{0}",
                  result)
              );result = runner.driver(
                  "GRjRYIvYwgua", 
                  "GRjRYIvYwgub"
              );
              Console.WriteLine(string.Format(
                  "TEST-6...{0}",
                  result)
              );result = runner.driver(
                  "8139910006809", 
                  "813:910006809"
              );
              Console.WriteLine(string.Format(
                  "TEST-7...{0}",
                  result)
              );result = runner.driver(
                  "100101", 
                  "200101"
              );
              Console.WriteLine(string.Format(
                  "TEST-8...{0}",
                  result)
              );result = runner.driver(
                  "rw", 
                  "rx"
              );
              Console.WriteLine(string.Format(
                  "TEST-9...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def lexicographically_next_string(s):
      if (s == ' '):
          return 'a'
      i = (len(s) - 1)
      while ((s[i] == 'z') and (i >= 0)):
          i -= 1
      if (i == (- 1)):
          s = (s + 'a')
      else:
          s = s.replace(s[i], chr((ord(s[i]) + 1)), 1)
      return s
source_cpp: string lexicographically_next_string(string s) {
    if ( s == "" ) return "a";
    int i = s . length ( ) - 1;
    while ( s [ i ] == 'z' && i >= 0 ) i --;
    if ( i == - 1 ) s = s + 'a';
    else s [ i ] ++;
    return s;
  }