A30052. 下列程序是二分法的程序，横线处应该填上（ ）。def binary_search(arr, target): left = 0 right = len(arr) - 1 while left <= right: mid = (left + right) // 2 _________________________ return -1

if arr[mid] == target:

      return mid

elif arr[mid] > target:

      right = mid - 1

if arr[mid] == target:

      return mid

elif arr[mid] > target:

      right = mid

else:

      left = mid

if arr[mid] == target:

      return mid

elif arr[mid] > target:

      right = mid - 1

else:

      left = mid + 1

if arr[mid] == target:

      return mid

else:

      left = mid + 1