title: Find The Number Occurring Odd Number Of Times
signature: class Solution {
  
      public int FindTheNumberOccurringOddNumberOfTimes(List<int> arr, int arr_size) {
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(List<int> arr, int arr_size, int expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                int pred_result = solution_cls.PLACEHOLDER_FN_NAME(arr, arr_size); 
                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(
                  new List<int>{1, 5, 5, 8, 14, 15, 17, 17, 18, 23, 23, 25, 26, 35, 36, 39, 51, 53, 56, 56, 60, 62, 64, 64, 65, 66, 67, 68, 71, 75, 80, 82, 83, 88, 89, 91, 91, 92, 93, 95, 99}, 31, 
                  1
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{-56, 98, 44, 30, -88, 18, 60, 86, 4, 16, 10, 64, -22, -86, -66, -16, 70, -44, 98, 78, -96, -66, 92, 10, 40, -16}, 19, 
                  -56
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{0, 0, 0, 0, 0, 1, 1, 1}, 6, 
                  0
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{36, 11, 83, 41, 42, 14, 46, 89, 91, 96, 57, 42, 74, 73, 9, 26, 79, 40, 31, 69, 44, 39, 14, 92, 34, 20, 52, 47, 14}, 25, 
                  36
              );
              Console.WriteLine(string.Format(
                  "TEST-3...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{-84, -84, -84, -78, -66, -62, -62, -36, -24, -10, -10, -8, -4, -2, 12, 14, 20, 22, 36, 42, 46, 66, 84, 96, 96, 98}, 23, 
                  -84
              );
              Console.WriteLine(string.Format(
                  "TEST-4...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1}, 19, 
                  1
              );
              Console.WriteLine(string.Format(
                  "TEST-5...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{11, 12, 14, 28, 42, 48, 50, 58, 67, 74, 86, 89, 95}, 7, 
                  11
              );
              Console.WriteLine(string.Format(
                  "TEST-6...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{52, -56, -6, 74, 10, 68, 74, 10, 16, -80, 82, -32, 6, -6, 82, 20}, 11, 
                  52
              );
              Console.WriteLine(string.Format(
                  "TEST-7...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, 31, 
                  0
              );
              Console.WriteLine(string.Format(
                  "TEST-8...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{4, 80, 92}, 1, 
                  4
              );
              Console.WriteLine(string.Format(
                  "TEST-9...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def find_the_number_occurring_odd_number_of_times(arr, arr_size):
      for i in range(0, arr_size):
          count = 0
          for j in range(0, arr_size):
              if (arr[i] == arr[j]):
                  count += 1
          if ((count % 2) != 0):
              return arr[i]
      return (- 1)
source_cpp: int find_the_number_occurring_odd_number_of_times(vector<int> arr, int arr_size) {
    for ( int i = 0;
    i < arr_size;
    i ++ ) {
      int count = 0;
      for ( int j = 0;
      j < arr_size;
      j ++ ) {
        if ( arr [ i ] == arr [ j ] ) count ++;
      }
      if ( count % 2 != 0 ) return arr [ i ];
    }
    return - 1;
  }