问从未排序列表中删除重复单词

EN

#include "bst.h"
#include <strings.h>
#include <stdlib.h>

#define LIST_TERMINATOR 1

static size_t i = 0;
static char **final_list;

static void insert(void *word)
{
    final_list[i++] = word;
}

char **unique_words(const char **words)
{
    //Binary tree containing the words
    BST unique;
    bst_init(&unique, (int(*)(const void *, const void *))strcasecmp);

    //Every word will be inserted at most 1 time
    while(*words != NULL){
        if(bst_insert(&unique, (void *)*words) == BST_NO_MEMORY){
            bst_free(&unique);
            return NULL;
        }

        ++words;
    }

    //Array to return
    final_list = malloc(sizeof(char *) * (unique.node_count + LIST_TERMINATOR));
    if(final_list == NULL){
        bst_free(&unique);
        return NULL;
    }

    //Collect words without sorting, so if the list is merged with another 
    //and passed again, the tree won't become a linked list
    if(bst_iterate_top_down(&unique, insert) == BST_NO_MEMORY){
        free(final_list);
        bst_free(&unique);
        return NULL;
    }
    final_list[i] = NULL;

    bst_free(&unique);

    //Clear state
    i = 0;

    return final_list;
}