二分查找就是待查找的列表进行分半搜索
如下所示
二分查找普通实现:
def erfen(alist, item):
start = 0
end = len(alist) - 1
while start <= end:
n = int((start + end) / 2)
if alist[n] == item:
return True
elif alist[n] > item:
end = n - 1
else:
start = n + 1
return False
alist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
print(erfen(alist,10))
print(erfen(alist, 3))
递归实现:
#import sys
#sys.setrecursionlimit(1000000)
"""解决maximum recursion depth exceeded error """
def erfen(alist,item):
if len(alist) == 0:
return False
else:
mid=int(len(alist)/2)
if alist[mid] == item :
return True
elif item < alist[mid]:
return erfen(alist[:mid],item)
else :
return erfen(alist[mid+1:],item)
alist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
print(erfen(alist,10))
print(erfen(alist, 3))