フォークスタックのPython実装

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]:
                self.heapList[i],self.heapList[i // 2] = self.heapList[i//2], self.heapList[i]
                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 > 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