Python 简单的实现二分查找
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2024-03-19 21:35:58
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def BinarySearch(alist, item):
'''
简单二分查找
:param alist:
:param item:
:return:
'''
first = 0
last = len(alist) - 1
found = False
while first <= last and not found:
midpoint = (first + last)//2
if alist[midpoint] == item:
found = True
else:
if item < alist[midpoint]:
last = midpoint - 1
else:
first = midpoint + 1
return found
def binarysearch(alist, item):
'''
递归二分法
:param alist: 有序列表
:param item: 待查询值
:return: True or False
'''
if len(alist) == 0:
return False
else:
middlepoint = len(alist) // 2
if alist[middlepoint] == item:
return True
else:
if item < alist[middlepoint]:
return binarysearch(alist[:middlepoint], item)
else:
return binarysearch(alist[middlepoint+1:], item)
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