binary heap

#include <stdio.h>

int array[100], n;

void insert(int num, int location);
void hapus(int num);
void display();

int main() {
    int choice, num, root = 0;
    int quit = 0;
    n = 0;
    while(!quit) {
        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:
                hapus(array[0]);
                break;
            case 3:
                display();
                break;
            case 4:
                quit = 1;
                break;
            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 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;
}

void hapus(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;
    }
}