title: Binary Search
signature: func binarySearch(arr []int, l int, r int, x int) int {
test_code: package main
  
  import (
      "fmt"
      "reflect"
      "math"
      "sort"
  )
  
  // SOLUTION CODE
  // ===================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE
  // ===================================
  func validateSolution(actual int, expected int) bool {
      return reflect.DeepEqual(actual,expected)
  }
  
  func driver(arr []int, l int, r int, x int, expected int) string {
      if validateSolution(PLACEHOLDER_FN_NAME(arr, l, r, x),expected) {
              return "PASSED"
      }
      return "FAILED"
  
  }
  
  func main() {
  
      // Use imports to avoid undefined errors
      var _ = reflect.DeepEqual
      _ = math.Abs
      _ = sort.Sort
      result := ""
      result = driver([]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)
      fmt.Printf("TEST-0...%s\n", result)
      
      result = driver([]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)
      fmt.Printf("TEST-1...%s\n", result)
      
      result = driver([]int{0, 1}, 
  	1, 
  	1, 
  	1, 1)
      fmt.Printf("TEST-2...%s\n", result)
      
      result = driver([]int{28, 84, 40, 81}, 
  	2, 
  	2, 
  	2, -1)
      fmt.Printf("TEST-3...%s\n", result)
      
      result = driver([]int{-66, -62, -60, -56, -56, -2, 40, 44, 50, 74, 82, 94}, 
  	8, 
  	6, 
  	8, -1)
      fmt.Printf("TEST-4...%s\n", result)
      
      result = driver([]int{1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1}, 
  	7, 
  	7, 
  	10, -1)
      fmt.Printf("TEST-5...%s\n", result)
      
      result = driver([]int{15, 26, 31, 36, 36, 61, 68, 72, 75, 79, 82, 98}, 
  	6, 
  	7, 
  	8, -1)
      fmt.Printf("TEST-6...%s\n", result)
      
      result = driver([]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)
      fmt.Printf("TEST-7...%s\n", result)
      
      result = driver([]int{0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1}, 
  	12, 
  	10, 
  	6, -1)
      fmt.Printf("TEST-8...%s\n", result)
      
      result = driver([]int{81, 47}, 
  	1, 
  	1, 
  	1, -1)
      fmt.Printf("TEST-9...%s\n", 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;
  }