typedef struct TrieNode
{
    // number of times this string occurs in the corpus
    int count;

    // 26 TrieNode pointers, one for each letter of the alphabet
    struct TrieNode *children[26];

    // the co-occurrence subtrie for this string
    struct TrieNode *subtrie;
} TrieNode;

TrieNode *createTrieNode(void)
{
    int i;
    TrieNode *node = NULL;
    node = malloc(sizeof(TrieNode));
    node->count = 0;
    for (i = 0; i <26; i++)
    {
        node->children[i] = NULL;
    }
    node->subtrie = NULL;

    return node;
}

TrieNode *insertString(TrieNode *root, char *str)
{
    if(*str == '\0')
        return root;
    TrieNode *temp = NULL;
    if(root->children[*str - 97] == NULL)
    {
        temp = createTrieNode();
        root->children[*str - 97] = temp;
    }
    //printf("%c\t%d\n", *str, *str - 97);
    insertString(root->children[*str - 97], str + 1);
    return root;
}