kukemuna-cs50/problems/2024/x/speller@20240320T211301.881757995Z

dictionary.c

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+// Implements a dictionary's functionality
+
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+
+#include "dictionary.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 = 35536;
+
+// Hash table
+node *table[N];
+
+// counter for words
+int wordcount = 0;
+
+// Returns true if word is in dictionary, else false
+bool check(const char *word)
+{
+    // TODO
+    // +1 for NUL character
+    char lword[strlen(word) + 1];
+
+    for (int i = 0; i < strlen(lword); i++)
+    {
+        lword[i] = tolower((word[i]));
+    }
+
+    // Set cursor to the head of approriate linked list
+    node *cursor = table[hash(lword)];
+
+    while (cursor != NULL)
+    {
+        if (strcasecmp(word, cursor->word) == 0)
+        {
+            return true;
+        }
+        cursor = cursor->next;
+    }
+    return false;
+}
+
+// Hashes word to a number
+unsigned int hash(const char *word)
+{
+    // TODO: Improve this hash function
+    // https://www.reddit.com/r/cs50/comments/1x6vc8/comment/cf9nlkn/
+    unsigned int hash = 0;
+    for (int i = 0, n = strlen(word); i < n; i++)
+        hash = (hash << 2) ^ word[i];
+    return hash % N;
+}
+
+// Loads dictionary into memory, returning true if successful, else false
+bool load(const char *dictionary)
+{
+    // TODO
+    // +1 for NUL character
+    char word[LENGTH + 1];
+
+    FILE *dict = fopen(dictionary, "r");
+    if (dict == NULL)
+    {
+        return false;
+    }
+
+    while (fscanf(dict, "%s", word) != EOF)
+    {
+        node *new_node = malloc(sizeof(node));
+
+        if (new_node == NULL)
+        {
+            unload();
+            return false;
+        }
+        else
+        {
+            // Copy word to node
+            strcpy(new_node->word, word);
+
+            // Get bucket index (linked list)
+            int n = hash(new_node->word);
+
+            // Insert to list
+            new_node->next = table[n];
+            table[n] = new_node;
+            wordcount++;
+        }
+    }
+    fclose(dict);
+
+    return true;
+}
+
+// Returns number of words in dictionary if loaded, else 0 if not yet loaded
+unsigned int size(void)
+{
+    // TODO
+    if (wordcount > 0)
+    {
+        return wordcount;
+    }
+    return 0;
+}
+
+// Unloads dictionary from memory, returning true if successful, else false
+bool unload(void)
+{
+    // TODO
+    // For each hashtable bucket
+    for (int i = 0; i < N; i++)
+    {
+        node *cursor = table[i];
+
+        // For each linked list node
+        while (cursor != NULL)
+        {
+            node *tmp = cursor;
+            cursor = cursor->next;
+            free(tmp);
+        }
+        free(cursor);
+    }
+    return true;
+}

dictionary.h

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+// Declares a dictionary's functionality
+
+#ifndef DICTIONARY_H
+#define DICTIONARY_H
+
+#include <stdbool.h>
+
+// Maximum length for a word
+// (e.g., pneumonoultramicroscopicsilicovolcanoconiosis)
+#define LENGTH 45
+
+// Prototypes
+bool check(const char *word);
+unsigned int hash(const char *word);
+bool load(const char *dictionary);
+unsigned int size(void);
+bool unload(void);
+
+#endif // DICTIONARY_H