Sean Flannigan - Hash-Tables

README.md

@@ -1,3 +1,4 @@
+<!-- https://github.com/LambdaSchool/Hash-Tables/pull/151 -->
 # Hash Tables
 
 Hash tables are arguably the single most important data structures in existence. Used to implement everything from objects in JavaScript and dictionaries in Python to Memcached over a distributed computer network, hash tables are beloved by programmers for providing key/value storage with constant big-O time complexity for insertion, deletion, and access.

basic_hashtable/b_hashtables.c

@@ -70,7 +70,9 @@ unsigned int hash(char *str, int max)
  ****/
 BasicHashTable *create_hash_table(int capacity)
 {
-  BasicHashTable *ht;
+  BasicHashTable *ht = malloc(sizeof(BasicHashTable));
+  ht->capacity = capacity;
+  ht->storage = calloc(capacity, sizeof(Pair *));
 
   return ht;
 }
@@ -84,6 +86,20 @@ BasicHashTable *create_hash_table(int capacity)
  ****/
 void hash_table_insert(BasicHashTable *ht, char *key, char *value)
 {
+  // create the pair to be inserted
+  Pair *insert_pair = create_pair(key, value);
+
+  // hash the value
+  int hashed = hash(key, ht->capacity);
+  Pair *current_pair = ht->storage[hashed];
+  if (ht->storage[hashed] != NULL) {
+    if (strcmp(current_pair->key, key) != 0) {
+      printf("warning!");
+      // handle collision tomorrow
+    }
+    destroy_pair(current_pair);
+  }
+  ht->storage[hashed] = insert_pair;
 
 }
 
@@ -94,7 +110,12 @@ void hash_table_insert(BasicHashTable *ht, char *key, char *value)
  ****/
 void hash_table_remove(BasicHashTable *ht, char *key)
 {
-
+  int hashed = hash(key, ht->capacity);
+  Pair *current_pair = ht->storage[hashed];
+  if (ht->storage[hashed] != NULL) {
+    destroy_pair(current_pair);
+    ht->storage[hashed] = NULL;
+  }
 }
 
 /****
@@ -104,6 +125,11 @@ void hash_table_remove(BasicHashTable *ht, char *key)
  ****/
 char *hash_table_retrieve(BasicHashTable *ht, char *key)
 {
+  int hashed = hash(key, ht->capacity);
+  Pair *current_pair = ht->storage[hashed];
+  if (ht->storage[hashed] != NULL) {
+    return current_pair->value;
+  }
   return NULL;
 }
 
@@ -114,7 +140,14 @@ char *hash_table_retrieve(BasicHashTable *ht, char *key)
  ****/
 void destroy_hash_table(BasicHashTable *ht)
 {
-
+  for (int i = 0; i < ht->capacity; i++) {
+    if (ht->storage[i] != NULL) {
+      destroy_pair(ht->storage[i]);
+      ht->storage[i] = NULL;
+    }
+  }
+  free(ht->storage);
+  free(ht);
 }
 
 

full_hashtable/hashtables.c

@@ -70,7 +70,9 @@ unsigned int hash(char *str, int max)
  ****/
 HashTable *create_hash_table(int capacity)
 {
-  HashTable *ht;
+  HashTable *ht = malloc(sizeof(HashTable));
+  ht->capacity = capacity;
+  ht->storage = calloc(capacity, sizeof(LinkedPair *));
 
   return ht;
 }
@@ -86,7 +88,22 @@ HashTable *create_hash_table(int capacity)
  ****/
 void hash_table_insert(HashTable *ht, char *key, char *value)
 {
-
+  LinkedPair *insert_pair = create_pair(key, value);
+
+  int hashed = hash(key, ht->capacity);
+
+  LinkedPair *current_pair = ht->storage[hashed];
+
+  if (ht->storage[hashed] != NULL) {
+    if (strcmp(current_pair->key, key) != 0) {
+      while (current_pair->next != NULL) {
+        current_pair = current_pair->next;
+      }
+      current_pair->next = insert_pair;
+      return;
+    }
+  }
+  ht->storage[hashed] = insert_pair;
 }
 
 /****
@@ -99,6 +116,19 @@ void hash_table_insert(HashTable *ht, char *key, char *value)
  ****/
 void hash_table_remove(HashTable *ht, char *key)
 {
+  int hashed = hash(key, ht->capacity);
+  LinkedPair *current_pair = ht->storage[hashed];
+  if (ht->storage[hashed] != NULL) {
+    while (current_pair->next != NULL) {
+      LinkedPair *next_pair = current_pair->next;
+      if (strcmp(current_pair->key, key) != 0) {
+        current_pair = current_pair->next;
+      }
+      // here they do match ---> now what
+      // even though they match, that doesnt mean the match->next is null
+      // need to point from previous element to next element
+    }
+  }
 
 }