递归二分法查找`
def binary_search(alist, item):
n = len(alist)
if 0 == n:
return False
mid = n // 2
if alist[mid] == item:
return True
elif item < alist[mid]:
return binary_search(alist[:mid], item)
else:
return binary_search(alist[mid + 1:], item)
if __name__ == '__main__':
alist = [1,2,3,4,5,6,7,8,]
print(binary_search(alist,54))
print(binary_search(alist, 2))
结果
非递归二分法查找
def binary_search2(alist, item):
start = 0
end = len(alist) - 1
while start <= end:
mid = (start + end) // 2
if alist[mid] == item:
return True
elif item < alist[mid]:
end = mid - 1
else:
start = mid + 1
return False
if __name__ == '__main__':
alist = [1,2,3,4,5,6,7,8,9]
print(binary_search2(alist,1))
print(binary_search2(alist,10))
结果