HeapDoubLinArr, C++ (gcc)

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//g++  7.4.0
//Sorting and searching template array using heap sort and linear search in double linked list
//heapSort, heapify codes credit to Geeks for Geeks
//template modifications,swap and test driver codes created by Rezaul Hoque on April 12,2021
//please contact at jewelmrh@yahoo.com
#include <iostream>
#include <bits/stdc++.h>
using namespace std;
template <class T>
class node{
public:
T val;
int p;
int q;
node<T>* next;
node<T>* prev;
void heapSort(node<T> a[], int n);
void heapify(node<T> a[],int n, int i);
int lins( node<T> a[], int n, T thing);
void swap(node<T>& x, node<T>& y);
};
template <class T>
int node<T>::lins(node<T> a[], int n, T thing)
{
for(int i=0; i<n; i++){
if(a[i].val ==thing) {

return i;
  }
}
return -1;

}
template <class T>
 void node<T>:: heapify(node<T> arr[], int n, int i)
{
    int largest = i; 
    int l = 2 * i + 1; 
    int r = 2 * i + 2; 
  
    
    if (l < n && arr[l].val> arr[largest].val)
        largest = l;
  
    
    if (r < n && arr[r].val> arr[largest].val)
        largest = r;
  
    
    if (largest != i) {
        swap(arr[i], arr[largest]);
  
        
        heapify(arr, n, largest);
    }
}
  
template <class T>
void node<T>:: heapSort(node<T> arr[], int n)
{
    
    for (int i = n / 2 - 1; i >= 0; i--)
        heapify(arr, n, i);
  
    
    for (int i = n - 1; i >= 0; i--) {
        
        swap(arr[0], arr[i]);
  
        
        heapify(arr, i, 0);
    }
}
template <class T>
void node<T>:: swap(node<T>& x, node<T>& y)
{
node<T> temp;
temp = x;
x=y;
y=temp;
}

int main()
{
const int max=3;
node<char>* a;

a = new node<char>[max];

a[0].prev=NULL;
a[2].next = NULL;
for(int i=0; i<max; i++)
{
  a[i].next = a[i+2].prev;
}
a[0].val={'E'};
a[1].val={'D'};
a[2].val={'C'};
a[0].p={4};
a[1].p={2};
a[2].p = {6};
a[0].q={5};
a[1].q={4};
a[2].q = {8};

cout<<"After heap sort:\n";
a->heapSort(a, 3);
for(int i=0; i<max; i++)
{
cout<<a[i].val<<"\t"<<a[i].p<<"\t"<<a[i].q<<endl;
cout<<"\n";
}
char thing;

cout<<"Enter the thing you look for:\n";
cin>>thing;
if(a->lins(a,3,thing) != -1)
  {
cout<<thing<<" is at a["<<a->lins(a, 3,thing)<<"].\n";
}
 else
    { 
      cout <<thing<<" is not found.\n";
  }
return 0;
}

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Compilation time: 1.52 sec, absolute running time: 0.18 sec, cpu time: 0.02 sec, memory peak: 5 Mb, absolute service time: 1,8 sec