def binary_search(list,item):
low = 0
high = len(list) -1#low和high用于跟踪要在其中查找的列表部分
while low <= high:
mid = (low + high) // 2 #//表示整数除法
guess = list[mid]
if guess == item:
return mid
if guess > item:
high = mid - 1
else:
low = mid + 1
return None
my_list = [1,3,5,7,9]
print(binary_search(my_list, 3))
print(binary_search(my_list, -1))
报错原因:列表索引必须是整型或者切片
解决办法:
1.将mid = (low + high) / 2
改写为mid = (low + high) // 2
注:" / “就表示 浮点数除法,返回浮点结果;” // "表示整数除法
2.强行转换为整型:
将mid = (low + high) / 2
改写为mid = int((low + high) / 2)