python-数据结构代码 二叉堆

Posted 2021-01-29 yangly

 

class BinHeap:
    def __init__(self):
        self.heapList = [0]
        self.currentSize = 0
    
    def percUp(self,i):
        while i // 2 > 0:
            if self.heapList[i] < self.heapList[i // 2]:
                tmp=self.heapList[i // 2]
                self.heapList[i // 2] = self.heapList[i]
                self.heapList[i] = tmp
            i = i // 2

    def insert(self,k):
        self.heapList.append(k)
        self.currentSize = self.currentSize + 1
        self.percUp(self.currentSize)

    def percDown(self,i):
        while(i*2)<=self.currentSize:
            mc=self.minChild(i)
            if self.heapList[i] > self.heapList[mc]:
                tmp=self.heapList[i]
                self.heapList[i]=self.heapList[mc]
                self.heapList[mc]=tmp
            i=mc

    def minChild(self,i):
        if i*2+1>self.currentSize:
            return i*2
        else:
            if self.heapList[i*2]<self.heapList[i*2+1]:
                return i*2
            else:
                return i*2+1

    def delMin(self):
        retval=self.heapList[1]
        self.heapList[1]=self.heapList[self.currentSize]
        self.currentSize=self.currentSize-1
        self.heapList.pop()
        self.percDown(1)
        return retval

    def buildHeap(self,alist):
        i=len(alist)//2
        self.currentSize=len(alist)
        self.heapList=[0]+alist[:]
        while (i>0):
            self.percDown(i)
            i=i-1
    
bh = BinHeap()
bh.buildHeap([9,5,6,2,3])

print(bh.delMin())
print(bh.delMin())
print(bh.delMin())
print(bh.delMin())
print(bh.delMin())