Here is the reference code for the Binary Heap Implementation. Make sure to refer to the video lecture for the full explanation!
The basic operations we will implement for our binary heap are as follows:
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