元素下沉 ,如果当前元素小于子元素中最小的,应该直接break吧 #9

# 删除堆顶元素后, 交换堆尾和空堆顶的位置并实现元素的下沉
def percDown(self, i):
    while (i*2) <= self.currentSize:
        mc = self.minChild(i)
        if self.heapList[i] > self.heapList[mc]:
            temp = self.heapList[i]
            self.heapList[i] = self.heapList[mc]
            self.heapList[mc] = temp
       else:
              break