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heap , min heap in py

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Adventurous Alligator answered on March 11, 2022 Popularity 10/10 Helpfulness 3/10

answer heap , min heap in py

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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 min-heap python

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Contributed on Jul 30 2022

Adventurous Alligator

0 Answers Avg Quality 2/10

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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

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Contributed on Aug 13 2022

Good Grasshopper

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 heap min or max

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Python's heap is a min heap.

Popularity 10/10 Helpfulness 1/10 Language whatever

Source: docs.python.org

Tags: heap

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Contributed on Jun 14 2022

Johan

0 Answers Avg Quality 2/10

python heapify

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-1

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

heap , min heap in py

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