搜索常见算法：顺序查找，二分法查找，哈希查找，下面是二分查找的实现方式
# coding:utf-8
# 二分查找的前提：只能对有序列进行查找
def binary_search(alist,item):
"""二分查找---递归实现"""
n = len(alist)
if n > 0:
mid = n//2
if item == alist[mid] :
return True
elif item < alist[mid]:
return binary_search(alist[:mid],item)
else:
return binary_search(alist[mid+1:], item)
else :
return False
def binary_search_2(alist,item):
"""二分查找---非递归版本"""
n = len(alist)
first = 0
last = n-1
while first <= last:
mid = (first + last)//2
if alist[mid] ==item:
return True,mid
elif item < alist[mid]:
last = mid - 1
else:
first = mid + 1
return False
if __name__ == "__main__":
a = [1,5,6,10,11,13,18,37,99]
print(a)
sorted_list_11 = binary_search(a,1)
print(sorted_list_11)
sorted_list_12= binary_search(a, 88)
print(sorted_list_12)
sorted_list_21 = binary_search_2(a, 18)
print(sorted_list_21)
sorted_list_22 = binary_search_2(a, 88)
print(sorted_list_22)
# [1, 5, 6, 10, 11, 13, 18, 37, 99]
# True
# False
# (True, 6)
# False
