#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

typedef struct _Node { // 12+ bytes
    int value;          // 4 bytes
    struct _Node* next; // 8 bytes
} Node;

#define log_int(n) printf("%s == %d\n", #n, n)

void print_list(const Node* head) {
    // good code quality: using a for loop
    for (const Node* node = head; node != NULL; node = node->next) {
        printf("[%d]->", node->value);
    }
    printf("NULL\n");
}

void destroy_list(Node* head) {
    Node* node = head;
    while (node != NULL) {
        Node* next = node->next;
        free(node);
        node = next;
    }
}

// pq_insert and remove_front effectively makes this a queue
void pq_insert(Node** a_head, int value) {
    Node* new_node = malloc(sizeof(*new_node));
    *new_node = (Node) { .next = NULL, .value = value };

    if (*a_head == NULL || (*a_head)->value >= value) {
        // from size 0 to size 1
        // OR if the new element is smaller than the old head
        new_node->next = *a_head;
        *a_head = new_node;
    } else {
        // search the list to find the node to insert after
        Node* node = *a_head;
        while (node->next != NULL && node->next->value < value) {
            node = node->next;
        }
        // insert at the location
        new_node->next = node->next;
        node->next = new_node;
    }
}

Node* remove_front(Node** a_head) {
    Node* node = *a_head;
    if (node == NULL) {
        return NULL;
    }
    *a_head = node->next;
    node->next = NULL;
    return node;
}

int get_size_of_list(const Node* head) {
    int size = 0;
    for (const Node* node = head; node != NULL; node = node->next) {
        size += 1;
    }
    return size;
}

int main(int argc, char* argv[]) {
    Node* head = NULL;
    print_list(head);

    pq_insert(&head, 2);
    print_list(head);

    pq_insert(&head, 1);
    print_list(head);

    pq_insert(&head, 3);
    print_list(head);
    print_list(head->next);

    pq_insert(&head, 343);
    pq_insert(&head, 34);
    pq_insert(&head, 6654);
    pq_insert(&head, 545);
    pq_insert(&head, 934);
    pq_insert(&head, 49);
    print_list(head);
    log_int(get_size_of_list(head));
    log_int(get_size_of_list(head->next));

    Node* node = remove_front(&head);
    print_list(head);
    print_list(node);
    destroy_list(node);

    node = remove_front(&head);
    print_list(head);
    print_list(node);
    destroy_list(node);

    pq_insert(&head, 1234);
    print_list(head);

    node = remove_front(&head);
    print_list(head);
    print_list(node);
    //destroy_list(node);

    destroy_list(head);

    return EXIT_SUCCESS;
}
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