Question

C++, I am not able to get this program to function correctly, ie not launching at all

#include <iostream>
#include <stdio.h>

int insert(int num, int location)
{
int parentnode;
while (location > 0)
{
parentnode =(location - 1)/2;
if (num <= array[parentnode])
{
array[location] = num;
return;
}
array[location] = array[parentnode];
location = parentnode;
}
array[0] = num;
}

int array[100], n;
using namespace std;
main()
{
int choice, num;
n = 0;
while(1)
{
printf("1.Insert the element \n");
printf("2.Delete the element \n");
printf("3.Display all elements \n");
printf("4.Quit \n");
printf("Enter your choice : ");
scanf("%d", &choice);
switch(choice)
{
case 1:
printf("Enter the element to be inserted to the list : ");
scanf("%d", &num);
insert(num, n);
n = n + 1;
break;
case 2:
printf("Enter the elements to be deleted from the list: ");
scanf("%d", &num);
delete(num);
break;
case 3:
display();
break;
case 4:
exit(0);
default:
printf("Invalid choice \n");
}
}
}

display()
{
int i;
if (n == 0)
{
printf("Heap is empty \n");
return;
}
for (i = 0; i < n; i++)
printf("%d ", array[i]);
printf("\n");
}

delete(int num)
{
int left, right, i, temp, parentnode;

for (i = 0; i < num; i++) {
if (num == array[i])
break;
}
if (num != array[i])
{
printf("%d not found in heap list\n", num);
return;
}
array[i] = array[n - 1];
n = n - 1;
parentnode =(i - 1) / 2;
if (array[i] > array[parentnode])
{
insert(array[i], i);
return;
}
left = 2 * i + 1;
right = 2 * i + 2;
while (right < n)
{
if (array[i] >= array[left] && array[i] >= array[right])
return;
if (array[right] <= array[left])
{
temp = array[i];
array[i] = array[left];
array[left] = temp;
i = left;
}
else
{
temp = array[i];
array[i] = array[right];
array[right] = temp;
i = right;
}
left = 2 * i + 1;
right = 2 * i + 2;
}
if (left == n - 1 && array[i])
{
temp = array[i];
array[i] = array[left];
array[left] = temp;
}
}

Answer 1

#include <iostream>
#include <stdio.h>

int array[100], n;
using namespace std;
void display();
void delete_elem(int num);


void heapify(int index,int n){
    if(index >= n)return;
    

    int left = 2*index;
    int right = 2*index + 1;
    int mx_ind = index;
    if(left < n and array[left] > array[mx_ind]){
        mx_ind = left;
    }
    if(right < n and array[right] > array[mx_ind]){
        mx_ind = right;
    }
    if(mx_ind != index){
        swap(array[mx_ind],array[index]);
        heapify(mx_ind,n);
    }

}
int insert(int num, int location)
{
    int parentnode;
    while (location > 0)
    {
        parentnode =(location - 1)/2;
        if (num <= array[parentnode])
        {
            array[location] = num;
            return location;
        }
        array[location] = array[parentnode];
        location = parentnode;
    }
    array[0] = num;
    return 0;
}

int main()
{
    int choice, num;
    n = 0;
    while(1)
    {
        printf("1.Insert the element \n");
        printf("2.Delete the element \n");
        printf("3.Display all elements \n");
        printf("4.Quit \n");
        printf("Enter your choice : ");
        scanf("%d", &choice);
        switch(choice)
        {
            case 1:
                printf("Enter the element to be inserted to the list : ");
                scanf("%d", &num);
                insert(num, n);
                n = n + 1;
                break;
            case 2:
                printf("Enter the elements to be deleted from the list: ");
                scanf("%d", &num);
                delete_elem(num);
                break;
            case 3:
                display();
                break;
            case 4:
                exit(0);
            default:
            printf("Invalid choice \n");
        }
    }
}

void display()
{
    int i;
    if (n == 0)
    {
        printf("Heap is empty \n");
        return;
    }
    for (i = 0; i < n; i++)
    printf("%d ", array[i]);
    printf("\n");
}


void delete_elem(int num)
{
    int left, right, i, temp, parentnode;

    for (i = 0; i < num; i++) {
        if (num == array[i])
        break;
    }
    if (num != array[i])
    {
        printf("%d not found in heap list\n", num);
        return;
    }
    array[i] = array[n - 1];
    n = n - 1;
    parentnode =(i - 1) / 2;
    if (array[i] > array[parentnode])
    {
        insert(array[i], i);
        return;
    }
    left = 2 * i + 1;
    right = 2 * i + 2;
    while (right < n)
    {
            if (array[i] >= array[left] && array[i] >= array[right])
                return;
            if (array[right] <= array[left])
            {
                temp = array[i];
                array[i] = array[left];
                array[left] = temp;
                i = left;
            }
            else
            {
                temp = array[i];
                array[i] = array[right];
                array[right] = temp;
                i = right;
            }
            left = 2 * i + 1;
            right = 2 * i + 2;
    }
    if (left == n - 1 && array[i])
    {
        temp = array[i];
        array[i] = array[left];
        array[left] = temp;
    }
}