it's my first time on here after a long time of following conversations and seeking help. In Pset5 Speller (CS50 2022), I have a weird situation. My code for dictionary.c works when I use the basic hashtable (just creating 26 keys), but when I try and optimise to make it faster (by creating 626, categorising by AA, AB, AC...ZZ) I get a seg fault.
My dictionary.c code is below. Any help or advice would be awesome!!!
// Implements a dictionary's functionality #include <ctype.h> #include <stdbool.h> #include <stdio.h> #include "dictionary.h" #include <stdlib.h> #include <string.h> #include <strings.h> // Represents a node in a hash table typedef struct node { char word[LENGTH + 1]; struct node *next; } node; // TODO: Choose number of buckets in hash table const unsigned int N = 26*26; // Hash table node *table[N]; // Declare count Variable unsigned int count = 0; // Returns true if word is in dictionary, else false bool check(const char *word) { int code = hash(word); // printf("check input word\n%s\n", word); for (node *tmp = table[code]; tmp != NULL; tmp = tmp->next) { //printf(" my readout\n%s\n%s\n readout done\n", word, tmp->word); if (strcasecmp(tmp->word, word) == 0) { return true; } } return false; } // Hashes word to a number unsigned int hash(const char *word) { // TODO: Tried to improve this hash function, but something goes wrong! return 26 * (toupper(word[0]) - 'A') + (toupper(word[1]) - 'A'); } // Loads dictionary into memory, returning true if successful, else false bool load(const char *dictionary) { // Open dictionary file FILE *file; file = fopen(dictionary, "r"); printf("the return value of fopen is: %p\n", fopen(dictionary, "r")); if (file == NULL) { return false; } char buffer[LENGTH + 1]; // Read strings one by one into variable buffer while (fscanf(file, "%s", buffer) != EOF) //printf("%s\n", buffer); //create a new node for this word { node *n = malloc(sizeof(node)); if (n == NULL) { free(n); fclose(file); return false; } //copy word into new node and initialise pointer to NULL //printf("%s\n", buffer); strcpy(n->word, buffer); n->next = NULL; // Hash the word in the buffer int code = hash(buffer); //printf("%i\n", code); // connect the new node to first in the list, then insert it at the front n->next = table[code]; table[code] = n; count++; } fclose(file); return true; } // Returns number of words in dictionary if loaded, else 0 if not yet loaded unsigned int size(void) { return count; } // Unloads dictionary from memory, returning true if successful, else false bool unload(void) { // declare two variables - cursor and tmp node *tmp = NULL; node *cursor = NULL; // go to each part of the hash table for(int i = 0; i < N; i++) { cursor = table[i]; tmp = table[i]; while(cursor != NULL) { tmp = cursor; cursor = cursor->next; free(tmp); } } return true; } 
