# Binary Heap Implementation¶

Here is the reference code for the Binary Heap Implementation. Make sure to refer to the video lecture for the full explanation!

### Binary Heap Operations¶

The basic operations we will implement for our binary heap are as follows:

• BinaryHeap() creates a new, empty, binary heap.
• insert(k) adds a new item to the heap.
• findMin() returns the item with the minimum key value, leaving item in the heap.
• delMin() returns the item with the minimum key value, removing the item from the heap.
• isEmpty() returns true if the heap is empty, false otherwise.
• size() returns the number of items in the heap.
• buildHeap(list) builds a new heap from a list of keys.
In [1]:
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

In [ ]: