剑指 Offer 41. 数据流中的中位数

Python：

class MedianFinder:

    def __init__(self):
        """
        initialize your data structure here.
        """
        self.stack=[]


    def addNum(self, num: int) -> None:
        self.stack.append(num) 
        def quick_sort(testlist,start,end):
            if start<end:
                i,j=start,end
                base=testlist[i]
                while i<j:
                    while i<j and testlist[j]>=base:
                        j-=1
                    testlist[i],testlist[j]=testlist[j],testlist[i]
                    while i<j and testlist[i]<=base:
                        i+=1
                    testlist[i],testlist[j]=testlist[j],testlist[i]
                testlist[i]=base
                quick_sort(testlist,start,i-1)
                quick_sort(testlist,i+1,end)
        quick_sort(self.stack,0,len(self.stack)-1)

    def findMedian(self) -> float:
        if not self.stack:
            return None
        elif len(self.stack)%2==0:
            index=len(self.stack)//2
            return (self.stack[index]+self.stack[index-1])/2.0
        elif len(self.stack)%2!=0:
            index=len(self.stack)//2
            return self.stack[index]