Data-Structure-Algorithm/15Heap.cpp at main · mayurgalhate/Data-Structure-Algorithm · GitHub

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#include<iostream>

using namespace std;

#include<queue>

class heap{

public:

int arr[100];

int size;

heap(){

arr[1] = -1;

size = 0;

}

void insert(int val){

size = size + 1;

int index = size;

arr[index] = val;

while(index > 1){

int parent = index/2;

if(arr[parent] < arr[index]){

swap(arr[parent], arr[index]);

index = parent;

}

else{

return;

}

void print(){

for (int i = 1; i <= size; i++)

{

cout << arr[i] << " ";

} cout << endl;

}

void deletefromHeap(){

if(size == 0){

cout << "nothing to delete" ;

return;

}

//step1: put last element in first

arr[1] = arr[size];

//step2: remove last element

size--;

//step3: take root node to its correct position

int i = 1;

while(i < size){

int leftindex = 2*i;

int rightindex = 2*i+1;

if(leftindex < size && arr[i] < arr[leftindex]){

swap(arr[i], arr[leftindex]);

i = leftindex;

}

else if(rightindex < size && arr[i] < arr[rightindex]){

swap(arr[i], arr[rightindex]);

i = rightindex;

}

else{

return;

}

void heapify(int arr[], int n, int i){

int largest = i;

// 1 base indexing logic if 0 base indexing then for left = 2*i+1 amd right = 2*i+2

int left = 2*i;

int right = 2*i+1;

//no need of <=

if(left <= n && arr[largest] < arr[left]){

largest = left;

}

//no need of <=

if(right <= n && arr[largest] < arr[right]){

largest = right;

}

if(largest != i){

swap(arr[largest], arr[i]);

heapify(arr, n, largest);

}

void heapSort(int arr[], int n){

int size = n;

while(size > 1){

//step1: swap

swap(arr[size], arr[1]);

size--;

//step2

heapify(arr, size, 1);

}

};

int main(){

heap h;

h.insert(50);

h.insert(55);

h.insert(53);

h.insert(52);

h.insert(54);

h.print();

h.deletefromHeap();

h.print();

int arr[6] = {-1, 54, 53, 55, 52, 50};

int n = 5;

// if 1 base indexing so below i = n/2 or if 0 base indexing then i = n/2-1

for (int i = n/2; i > 0; i--){

h.heapify(arr, n, i);

}

cout << "printing the array now: " << endl ;

for (int i = 1; i <= n; i++)

{

cout << arr[i] << " " ;

}cout << endl;

h.heapSort(arr, n);

cout << "printing the Sorted array now: " << endl ;

for (int i = 1; i <= n; i++)

{

cout << arr[i] << " " ;

}

cout << endl;

cout << " Max heapusing Priority Queue " << endl;

priority_queue<int> pq;

pq.push(5);

pq.pop();

pq.push(4);

pq.push(2);

pq.push(9);

cout << "Top :" << pq.top() << endl;

cout << "size :" << pq.size() << endl;

string ans = (pq.empty()) ? "empty" : "Notempty";

cout << ans ;

cout << endl;

cout << "Using Min heap " << endl;

priority_queue<int, vector<int>, greater<int>> minheap;

minheap.push(5);

minheap.pop();

minheap.push(4);

minheap.push(2);

minheap.push(9);

cout << "Top :" << minheap.top() << endl;

cout << "size :" << minheap.size() << endl;

string res = (minheap.empty()) ? "empty" : "Notempty";

cout << res ;

return 0;

}

Data-Structure-Algorithm/15Heap.cpp at main · mayurgalhate/Data-Structure-Algorithm · GitHub

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