二叉搜索：
第一步，先取中间位置值进行比较；
第二步，在大于或者小于的一部分进行比较；
重复第一、二步。
def binarySearch(target,sortedLyst):
left = 0
right = len(sortedLyst) -1
while left<= right:
print(left,right)
midpoint = (left+right)//2
print(midpoint,target)
if target == sortedLyst[midpoint]:
return midpoint
elif target < sortedLyst[midpoint]:
right = midpoint -1
else:
left = midpoint +1
return -1
lys = [20,44,48,55,62,66,74,88,93,99]
binarySearch(90,lys)
binarySearch(44,lys)
结果：
0 9
4 90
5 9
7 90
8 9
8 90
0 9
4 44
0 3
1 44
python 内建类对象比较。eq ==; it 小于； gt 大于。
class SavingAccount(object):
def __init__(self,name,pin,balance=0.0,num=0.0):
self._name = name
self._pin = pin
self._balance = balance
self._num = num
def __eq__(self, other):
return self._num==other._num
def __lt__(self, other):
print(other._name,other._balance,other._num)
print(self._name,self._balance,self._num)
return self._num < other._num
def __gt__(self, other):
print(other._name, other._balance, other._num)
print(self._name, self._balance, self._num)
return self._num > other._num
def __str__(self):
return str(self._name + self._pin+ str(self._balance)+str(self._num))
