title: Count Natural Numbers Whose Permutation Greater Number
signature: class Solution {
  
      public int CountNaturalNumbersWhosePermutationGreaterNumber(int n) {
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(int actual, int expected){
              return new JavaScriptSerializer().Serialize(actual) == new JavaScriptSerializer().Serialize(expected);
          }
  
          public string driver(int n, int expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                int pred_result = solution_cls.PLACEHOLDER_FN_NAME(n); 
                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(
                  69, 
                  48
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  72, 
                  48
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  88, 
                  52
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );result = runner.driver(
                  7, 
                  7
              );
              Console.WriteLine(string.Format(
                  "TEST-3...{0}",
                  result)
              );result = runner.driver(
                  66, 
                  45
              );
              Console.WriteLine(string.Format(
                  "TEST-4...{0}",
                  result)
              );result = runner.driver(
                  34, 
                  28
              );
              Console.WriteLine(string.Format(
                  "TEST-5...{0}",
                  result)
              );result = runner.driver(
                  23, 
                  20
              );
              Console.WriteLine(string.Format(
                  "TEST-6...{0}",
                  result)
              );result = runner.driver(
                  37, 
                  31
              );
              Console.WriteLine(string.Format(
                  "TEST-7...{0}",
                  result)
              );result = runner.driver(
                  33, 
                  27
              );
              Console.WriteLine(string.Format(
                  "TEST-8...{0}",
                  result)
              );result = runner.driver(
                  21, 
                  18
              );
              Console.WriteLine(string.Format(
                  "TEST-9...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def count_natural_numbers_whose_permutation_greater_number(n):
      result = 0
      for i in range(1, 10):
          s = []
          if (i <= n):
              s.append(i)
              result += 1
          while (len(s) != 0):
              tp = s[(- 1)]
              s.pop()
              for j in range((tp % 10), 10):
                  x = ((tp * 10) + j)
                  if (x <= n):
                      s.append(x)
                      result += 1
      return result
source_cpp: int count_natural_numbers_whose_permutation_greater_number(int n) {
    int result = 0;
    for ( int i = 1;
    i <= 9;
    i ++ ) {
      stack < int > s;
      if ( i <= n ) {
        s . push ( i );
        result ++;
      }
      while ( ! s . empty ( ) ) {
        int tp = s . top ( );
        s . pop ( );
        for ( int j = tp % 10;
        j <= 9;
        j ++ ) {
          int x = tp * 10 + j;
          if ( x <= n ) {
            s . push ( x );
            result ++;
          }
        }
      }
    }
    return result;
  }