def binary_search(my_list, low, high, elem):
   if high >= low:
       mid = (high + low) // 2
       if my_list[mid] == elem:
          return mid
       elif my_list[mid] > elem:
          return binary_search(my_list, low, mid - 1, elem)
       else:
          return binary_search(my_list, mid + 1, high, elem)
   else:
       return -1

my_list = [ 1, 9, 11, 21, 34, 54, 67, 90 ]
elem_to_search = 1
print("该列表为")
print(my_list)

my_result = binary_search(my_list,0,len(my_list)-1,elem_to_search)

if my_result != -1:
   print("该元素位于索引", str(my_result))
else:
   print("未找到该元素！")

该列表为
[1, 9, 11, 21, 34, 54, 67, 90]
该元素位于索引0