title: Find The Number Occurring Odd Number Of Times 1
signature: class Solution {
  
      public int FindTheNumberOccurringOddNumberOfTimes1(List<int> arr, int 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 size, int expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                int pred_result = solution_cls.PLACEHOLDER_FN_NAME(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>{49, 90}, 1, 
                  49
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{-96, 94, 92, -24, 48, 54, -30, -86, 28, -18, 12, -64, -36, 68, 68, -78, -6, 30, -84, 20, 52, -36, 40, -62, 90, -48, 86, 98, 12, 44, 98, -66, 52, 34, 36, 76, -50, -20, -20, -20}, 39, 
                  -96
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{0, 1}, 1, 
                  0
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{79, 55, 18, 99, 38, 93, 19, 49, 21, 74, 16, 76, 82, 52, 86, 17, 42, 9, 6, 63, 1, 40, 75, 59, 41, 81}, 23, 
                  79
              );
              Console.WriteLine(string.Format(
                  "TEST-3...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{-90, -84, -82, -68, -66, -66, -60, -60, -48, -44, -36, -34, -30, -16, -14, -12, -10, -6, 2, 10, 10, 14, 22, 26, 30, 34, 46, 50, 52, 62, 64, 64, 66, 72, 74, 78, 78, 82, 84, 88, 92}, 23, 
                  -90
              );
              Console.WriteLine(string.Format(
                  "TEST-4...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1}, 18, 
                  1
              );
              Console.WriteLine(string.Format(
                  "TEST-5...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{2, 4, 5, 7, 7, 18, 18, 23, 23, 25, 25, 31, 41, 43, 45, 46, 52, 52, 55, 64, 69, 69, 80, 81, 84, 90, 91, 93, 94, 94, 94, 94, 96, 98, 99}, 20, 
                  2
              );
              Console.WriteLine(string.Format(
                  "TEST-6...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{86, 66, -8, 2, -18, -22, 38, 4, -38, -54, 78, 64, 78, 20, -32, 84, -70, 66, -46, 12, -12, 8, 44, 14, 20}, 20, 
                  86
              );
              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, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, 21, 
                  0
              );
              Console.WriteLine(string.Format(
                  "TEST-8...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{11, 4, 98, 38, 20, 41, 1, 8}, 7, 
                  11
              );
              Console.WriteLine(string.Format(
                  "TEST-9...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def find_the_number_occurring_odd_number_of_times_1(arr, size):
      Hash = dict()
      for i in range(size):
          Hash[arr[i]] = (Hash.get(arr[i], 0) + 1)
      for i in Hash:
          if ((Hash[i] % 2) != 0):
              return i
      return (- 1)
source_cpp: int find_the_number_occurring_odd_number_of_times_1(vector<int> arr, int size) {
    unordered_map < int, int > hash;
    for ( int i = 0;
    i < size;
    i ++ ) {
      hash [ arr [ i ] ] ++;
    }
    for ( auto i : hash ) {
      if ( i . second % 2 != 0 ) {
        return i . first;
      }
    }
    return - 1;
  }