二叉搜索：
第一步，先取中間位置值進行比較；
第二步，在大于或者小于的一部分進行比較；
重復第一、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)

結果：

0 9
4 90
5 9
7 90
8 9
8 90
0 9
4 44
0 3
1 44

python 內建類對象比較。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))