3) 이진탐색 (Binary search)

##### 3. 이진탐색 : 절반으로 잘라가며 요소 찾기

def binary_search(element, some_list):
    start_index = 0
    end_index = len(some_list) - 1

    while start_index <= end_index:
        midpoint = (start_index + end_index) // 2
        if some_list[midpoint] == element:
            return midpoint
        elif some_list[midpoint] > element:
            end_index = midpoint - 1
        else:
            start_index = midpoint + 1
    return None


print(binary_search(2, [2, 3, 5, 7, 11]))
print(binary_search(0, [2, 3, 5, 7, 11]))
print(binary_search(5, [2, 3, 5, 7, 11]))
print(binary_search(3, [2, 3, 5, 7, 11]))
print(binary_search(11, [2, 3, 5, 7, 11]))