title: Binary Search
signature: class Solution {
  
      public int BinarySearch(List<int> arr, int l, int r, int x) {
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 l, int r, int x, int expected){
              try{
                PLACEHOLDER_CLS_NAME solution_cls = new PLACEHOLDER_CLS_NAME();
                int pred_result = solution_cls.PLACEHOLDER_FN_NAME(arr, l, r, x); 
                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>{3, 4, 4, 8, 9, 13, 13, 15, 18, 27, 30, 32, 42, 48, 50, 52, 56, 66, 69, 69, 77, 84, 84, 93}, 19, 12, 22, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-0...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{52, -58, -22, -80, 44, -52, -34, 94, -34, -74, 42, 60, -62, 70, 98, 32, 10, 94, 26, 56, -48, -50, 42, 2, 46, 28, -68, -16, -96, -12, 66, -46, 74, -60, -52, 28, -92, -78, 32, 28, 16, 34, 30, -60, -14}, 40, 35, 44, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-1...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{0, 1}, 1, 1, 1, 
                  1
              );
              Console.WriteLine(string.Format(
                  "TEST-2...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{28, 84, 40, 81}, 2, 2, 2, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-3...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{-66, -62, -60, -56, -56, -2, 40, 44, 50, 74, 82, 94}, 8, 6, 8, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-4...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1}, 7, 7, 10, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-5...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{15, 26, 31, 36, 36, 61, 68, 72, 75, 79, 82, 98}, 6, 7, 8, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-6...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{0, -82, -94, 48, 48, -96, 14, 66, 76, -30, 86, 28, -28, -66, -64, 92, -94, -66, 86, 26, 8, 94, -82, -80, 4, -26, 76, -46, 72, 88, -6, 8, -30, 40, -88, 2, -40, -98, -22, -20, 4, -12, 54, -20, -36, 12}, 38, 33, 39, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-7...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1}, 12, 10, 6, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-8...{0}",
                  result)
              );result = runner.driver(
                  new List<int>{81, 47}, 1, 1, 1, 
                  -1
              );
              Console.WriteLine(string.Format(
                  "TEST-9...{0}",
                  result)
              );
          }
      }
  }
  
source_py: def binary_search(arr, l, r, x):
      if (r >= l):
          mid = (l + ((r - l) // 2))
          if (arr[mid] == x):
              return mid
          elif (arr[mid] > x):
              return binary_search(arr, l, (mid - 1), x)
          else:
              return binary_search(arr, (mid + 1), r, x)
      else:
          return (- 1)
source_cpp: int binary_search(vector<int> arr, int l, int r, int x) {
    if ( r >= l ) {
      int mid = l + ( r - l ) / 2;
      if ( arr [ mid ] == x ) return mid;
      if ( arr [ mid ] > x ) return binary_search ( arr, l, mid - 1, x );
      return binary_search ( arr, mid + 1, r, x );
    }
    return - 1;
  }