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how to implement heap in python

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Good Grasshopper answered on September 4, 2021 Popularity 10/10 Helpfulness 3/10

answer how to implement heap in python

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how to implement heap in python

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# Python3 program to demonstrate working of heapq
  
from heapq import heapify, heappush, heappop
  
# Creating empty heap
heap = []
heapify(heap)
  
# Adding items to the heap using heappush function
heappush(heap, 10)
heappush(heap, 30)
heappush(heap, 20)
heappush(heap, 400)
  
# printing the value of minimum element
print("Head value of heap : "+str(heap[0]))
  
# printing the elements of the heap
print("The heap elements : ")
for i in heap:
    print(i, end = ' ')
print("\n")
  
element = heappop(heap)
  
# printing the elements of the heap
print("The heap elements : ")
for i in heap:
    print(i, end = ' ')

Popularity 10/10 Helpfulness 3/10 Language python

Source: www.geeksforgeeks.org

Tags: heap python

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Contributed on Aug 13 2022

Good Grasshopper

0 Answers Avg Quality 2/10

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heap , min heap in py

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# A Python program to demonstrate common binary heap operations
  
# Import the heap functions from python library
from heapq import heappush, heappop, heapify 
  
# heappop - pop and return the smallest element from heap
# heappush - push the value item onto the heap, maintaining
#             heap invarient
# heapify - transform list into heap, in place, in linear time
  
# A class for Min Heap
class MinHeap:
      
    # Constructor to initialize a heap
    def __init__(self):
        self.heap = [] 
  
    def parent(self, i):
        return (i-1)/2
      
    # Inserts a new key 'k'
    def insertKey(self, k):
        heappush(self.heap, k)           
  
    # Decrease value of key at index 'i' to new_val
    # It is assumed that new_val is smaller than heap[i]
    def decreaseKey(self, i, new_val):
        self.heap[i]  = new_val 
        while(i != 0 and self.heap[self.parent(i)] > self.heap[i]):
            # Swap heap[i] with heap[parent(i)]
            self.heap[i] , self.heap[self.parent(i)] = (
            self.heap[self.parent(i)], self.heap[i])
              
    # Method to remove minium element from min heap
    def extractMin(self):
        return heappop(self.heap)
  
    # This functon deletes key at index i. It first reduces
    # value to minus infinite and then calls extractMin()
    def deleteKey(self, i):
        self.decreaseKey(i, float("-inf"))
        self.extractMin()
  
    # Get the minimum element from the heap
    def getMin(self):
        return self.heap[0]
  
# Driver pgoratm to test above function
heapObj = MinHeap()
heapObj.insertKey(3)
heapObj.insertKey(2)
heapObj.deleteKey(1)
heapObj.insertKey(15)
heapObj.insertKey(5)
heapObj.insertKey(4)
heapObj.insertKey(45)
  
print heapObj.extractMin(),
print heapObj.getMin(),
heapObj.decreaseKey(2, 1)
print heapObj.getMin()
  
# This code is contributed by Nikhil Kumar Singh(nickzuck_007)

Popularity 10/10 Helpfulness 3/10 Language python

Source: www.geeksforgeeks.org

Tags: heap

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Contributed on Jul 30 2022

Adventurous Alligator

0 Answers Avg Quality 2/10

heapsort python

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def buildHeap(lista, n):
    for i in range(n//2 - 1, -1, -1):
        heapify(lista, n, i)

def heapify(lista, n, i):
    largest = i  
    left = (2 * i) + 1    
    right = (2 * i) + 2 

    if left < n and lista[largest] < lista[left]:
        largest = left

    if right < n and lista[largest] < lista[right]:
        largest = right

    if largest != i:
        lista[i], lista[largest] = lista[largest], lista[i] 
        heapify(lista, n, largest) 

def heapSort(lista):
    n = len(lista)
    buildHeap(lista, n)
    
    for i in range(n-1, 0, -1):
        lista[i], lista[0] = lista[0], lista[i]
        heapify(lista, i, 0)

Popularity 10/10 Helpfulness 2/10 Language python

Source: Grepper

Tags: heapsort heapsor

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Contributed on Sep 04 2021

Federiko98

0 Answers Avg Quality 2/10

python implementation of Min Heap

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# Python3 implementation of Min Heap
 
import sys
 
class MinHeap:
 
    def __init__(self, maxsize):
        self.maxsize = maxsize
        self.size = 0
        self.Heap = [0]*(self.maxsize + 1)
        self.Heap[0] = -1 * sys.maxsize
        self.FRONT = 1
 
    # Function to return the position of
    # parent for the node currently
    # at pos
    def parent(self, pos):
        return pos//2
 
    # Function to return the position of
    # the left child for the node currently
    # at pos
    def leftChild(self, pos):
        return 2 * pos
 
    # Function to return the position of
    # the right child for the node currently
    # at pos
    def rightChild(self, pos):
        return (2 * pos) + 1
 
    # Function that returns true if the passed
    # node is a leaf node
    def isLeaf(self, pos):
        return pos*2 > self.size
 
    # Function to swap two nodes of the heap
    def swap(self, fpos, spos):
        self.Heap[fpos], self.Heap[spos] = self.Heap[spos], self.Heap[fpos]
 
    # Function to heapify the node at pos
    def minHeapify(self, pos):
 
        # If the node is a non-leaf node and greater
        # than any of its child
        if not self.isLeaf(pos):
            if (self.Heap[pos] > self.Heap[self.leftChild(pos)] or
               self.Heap[pos] > self.Heap[self.rightChild(pos)]):
 
                # Swap with the left child and heapify
                # the left child
                if self.Heap[self.leftChild(pos)] < self.Heap[self.rightChild(pos)]:
                    self.swap(pos, self.leftChild(pos))
                    self.minHeapify(self.leftChild(pos))
 
                # Swap with the right child and heapify
                # the right child
                else:
                    self.swap(pos, self.rightChild(pos))
                    self.minHeapify(self.rightChild(pos))
 
    # Function to insert a node into the heap
    def insert(self, element):
        if self.size >= self.maxsize :
            return
        self.size+= 1
        self.Heap[self.size] = element
 
        current = self.size
 
        while self.Heap[current] < self.Heap[self.parent(current)]:
            self.swap(current, self.parent(current))
            current = self.parent(current)
 
    # Function to print the contents of the heap
    def Print(self):
        for i in range(1, (self.size//2)+1):
            print(" PARENT : "+ str(self.Heap[i])+" LEFT CHILD : "+
                                str(self.Heap[2 * i])+" RIGHT CHILD : "+
                                str(self.Heap[2 * i + 1]))
 
    # Function to build the min heap using
    # the minHeapify function
    def minHeap(self):
 
        for pos in range(self.size//2, 0, -1):
            self.minHeapify(pos)
 
    # Function to remove and return the minimum
    # element from the heap
    def remove(self):
 
        popped = self.Heap[self.FRONT]
        self.Heap[self.FRONT] = self.Heap[self.size]
        self.size-= 1
        self.minHeapify(self.FRONT)
        return popped
 
# Driver Code
if __name__ == "__main__":
     
    print('The minHeap is ')
    minHeap = MinHeap(15)
    minHeap.insert(5)
    minHeap.insert(3)
    minHeap.insert(17)
    minHeap.insert(10)
    minHeap.insert(84)
    minHeap.insert(19)
    minHeap.insert(6)
    minHeap.insert(22)
    minHeap.insert(9)
    minHeap.minHeap()
 
    minHeap.Print()
    print("The Min val is " + str(minHeap.remove()))

Popularity 10/10 Helpfulness 2/10 Language python

Source: www.geeksforgeeks.org

Tags: implementation impl

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Contributed on Mar 11 2022

Good Gentoo

0 Answers Avg Quality 2/10

python heapify

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Input: nums = [1,3,2,3,1]
Output: 2
Explanation: The reverse pairs are:
(1, 4) --> nums[1] = 3, nums[4] = 1, 3 > 2 * 1
(3, 4) --> nums[3] = 3, nums[4] = 1, 3 > 2 * 1

Popularity 10/10 Helpfulness 1/10 Language python

Source: leetcode.com

Tags: python py

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Contributed on Mar 28 2023

Mehari Tesfaye

0 Answers Avg Quality 2/10

what is heapq in python

Comment

Heap queue is a special tree structure in which each parent node is less than or equal to its child node. In python it is implemented using the heapq module. It is very useful in implementing priority queues where the queue item with higher weight is given more priority in processing

Popularity 10/10 Helpfulness 1/10 Language python

Source: Grepper

Tags: heapq heap

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Contributed on Jul 17 2022

jp98

0 Answers Avg Quality 2/10

how to implement heap in python

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heapsort python

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what is heapq in python

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