查找算法
二分查找算法
1 def binary_search(alist, item): 2 binary_index = int(len(alist)/2) 3 if alist == []: 4 return None 5 elif alist[binary_index] > item: 6 return binary_search(alist[:binary_index], item) 7 elif alist[binary_index] < item: 8 result = binary_search(alist[binary_index + 1:], item) 9 return None if result is None else result + binary_index + 1 10 elif alist[binary_index] == item: 11 return binary_index