sort list

#include <stdio.h>
#include <stdlib.h>
typedef struct cell_t cell_t;
struct cell_t {
  int key;
  cell_t *next;
};
typedef struct {
  int key;
} node_t;
cell_t *new_cell(int key) {
  cell_t *new = (cell_t *) malloc(sizeof(cell_t));
  new->key = key;
  new->next = NULL;
  return new;
}
cell_t *add_cell(cell_t *first, int key) {
  cell_t *p, *prev, *new = new_cell(key);
  for (p = first, prev = NULL; p; prev = p, p = p->next)
    if (p->key > key) break;
  if (!p && !prev) {
    return new;
  } else if (!p && prev) {
    prev->next = new;
    return first;
  } else if (p && !prev) {
    new->next = p;
    return new;
  } else {
    prev->next = new;
    new->next = p;
    return first;
  }
}
void puts_cell(cell_t *first) {
  cell_t *p;
  printf("[");
  for (p = first; p; p = p->next) {
    printf("%d", p->key);
    if (p->next) printf(", ");
  }
  printf("]\n");
}
node_t *new_node(int key) {
  node_t *new = (node_t *) malloc(sizeof(node_t));
  new->key = key;
  return new;
}
node_t **add_node(node_t **prime, int key, int *count) {
  node_t *new = new_node(key);
  prime = realloc(prime, ++(*count) * sizeof(node_t *));
  prime[*count - 1] = new;
  return prime;
}
void puts_node(node_t **prime, int count) {
  int i;
  printf("[");
  for (i = 0; i < count; i++) {
    printf("%d", prime[i]->key);
    if (i < count - 1) printf(", ");
  }
  printf("]\n");
}
int compare_node(const void *p1, const void *p2) {
  node_t **q1 = (node_t **) p1;
  node_t **q2 = (node_t **) p2;
  return (*q1)->key - (*q2)->key;
}
int main(void) {
  int a[] = { 19, 15, 18, 2, 6, 12, 19, 26, 5, 20 };
  int i;
  cell_t *first = NULL;
  node_t **prime = NULL;
  int count = 0;
  puts("Cell");
  for (i = 0; i < sizeof(a) / sizeof(int); i++) {
    first = add_cell(first, a[i]);
    puts_cell(first);
  }
  puts("Node");
  for (i = 0; i < sizeof(a) / sizeof(int); i++) {
    prime = add_node(prime, a[i], &count);
    puts_node(prime, count);
  }
  puts("sort");
  qsort(prime, count, sizeof(node_t *), compare_node);
  puts_node(prime, count);
  return 0;
}