adds ts for tree searches

c/hash-table.c

@@ -2,19 +2,38 @@
 #include <stdlib.h>
 #include <string.h>
 
+#define MAX_HASH_TABLE_SIZE 16
+
+typedef struct KV {
+    char *key;
+    char *value;
+} KV;
+
+typedef struct Node {
+    KV           kv;
+    struct Node *next;
+} Node;
+
 typedef struct HashTable {
-    char *data[16];
+    Node *data[MAX_HASH_TABLE_SIZE];
 } HashTable;
 
 HashTable *new_hashtable() {
     HashTable *ht = malloc(sizeof(HashTable));
-    for (int i = 0; i < 16; i++) {
+    for (int i = 0; i < MAX_HASH_TABLE_SIZE; i++) {
         ht->data[i] = NULL;
     }
 
     return (ht);
 }
 
+Node *new_node() {
+    Node *node = malloc(sizeof(Node));
+    node->next = NULL;
+
+    return (node);
+}
+
 int get_index_for_letter(char letter) {
     if (letter >= 'a' && letter <= 'z') {
         return (letter - 'a') + 1;
@@ -35,35 +54,83 @@ int hash(char *word) {
     return accum % 16;
 }
 
-char *get(HashTable *h, char *key) {
-    int hash_val = hash(key);
-    return h->data[hash_val];
-}
-
-void insert(HashTable *h, char *key, char *value) {
-    int hashed_key = hash(key);
-
-    if (h->data[hashed_key] != NULL) {
-        fprintf(stderr, "ERROR: collision!");
-        exit(1);
+KV *find_KV_in_ht(HashTable h, char *key) {
+    for (size_t i = 0; i < MAX_HASH_TABLE_SIZE; i++) {
+        if ((h.data[i] != NULL) && (strcmp(h.data[i]->kv.key, key) == 0)) {
+            return (&h.data[i]->kv);
+        }
     }
 
-    h->data[hashed_key] = value;
+    return (NULL);
 }
 
-void delete(HashTable *h, char *key) {
-    int hashed_key = hash(key);
-    h->data[hashed_key] = NULL;
+char *get_value(HashTable ht, char *key) {
+    int hash_key = hash(key);
+
+    Node *node_at_hash = ht.data[hash_key];
+
+    if (node_at_hash == NULL) {
+        fprintf(stderr, "ERROR: key not found in hashtable");
+        return;
+    }
+
+    // if next is NULL then this is the only at this hash so just return it
+    if (node_at_hash->next == NULL) {
+        return node_at_hash->kv.value;
+    }
+
+    return kv->value;
 }
 
+void insert_kv(HashTable *ht, char *key, char *value) {
+    int hashed_key = hash(key);
+
+    Node *current = ht->data[hashed_key];
+
+    while (current) {
+        if (strcmp(current->kv.key, key) == 0) {
+            current->kv.value = value;
+            return;
+        }
+
+        current = current->next;
+    }
+
+    Node *new = new_node();
+    new->kv.key = key;
+    new->kv.value = value;
+    new->next = current;
+    ht->data[hashed_key] = new;
+}
+
+// char *get(HashTable *h, char *key) {
+//     int hash_val = hash(key);
+//     return h->data[hash_val];
+// }
+
+// void insert(HashTable *h, char *key, char *value) {
+//     int hashed_key = hash(key);
+
+//     if (h->data[hashed_key] != NULL) {
+//         fprintf(stderr, "ERROR: collision!");
+//         exit(1);
+//     }
+
+//     h->data[hashed_key] = value;
+// }
+
+// void delete(HashTable *h, char *key) {
+//     int hashed_key = hash(key);
+//     h->data[hashed_key] = NULL;
+// }
+
 int main() {
-    HashTable *hash_table = new_hashtable();
-    char      *key = "hello";
-    insert(hash_table, key, "world");
-    insert(hash_table, "hlleo", "world");
-    char *res = get(hash_table, "hello");
+    HashTable *h = new_hashtable();
 
-    printf("the value at key '%s' is '%s'", key, res);
+    // test
+    insert_kv(h, "hello", "world");
+    char *result = get_value(*h, "hello");
+    printf("the value corresponding to the key 'hello' is: '%s'", result);
 
     return 0;
 }

ts/bfs.test.ts

@@ -0,0 +1,38 @@
+import { tree } from "./tree"
+
+type BinaryNode<T> = {
+    value: T;
+    left: BinaryNode<T> | null;
+    right: BinaryNode<T> | null;
+};
+
+
+function bfs(head: BinaryNode<number> | null, needle: number): boolean {
+    const q: (BinaryNode<number> | null)[] = [head];
+
+    while (q.length) {
+        const current = q.shift() as BinaryNode<number>;
+
+        if (current.value === needle) {
+            return true;
+        }
+
+        if (current.left) {
+            q.push(current.left);
+        }
+
+        if (current.right) {
+            q.push(current.right);
+        }
+    }
+
+    return false;
+}
+
+
+test("bfs search works a number of values", function () {
+    expect(bfs(tree, 20)).toEqual(true);
+    expect(bfs(tree, -20)).toEqual(false);
+    expect(bfs(tree, 10)).toEqual(true);
+    expect(bfs(tree, 7)).toEqual(true);
+})

ts/tree.ts

@@ -0,0 +1,47 @@
+type BinaryNode<T> = {
+    value: T;
+    left: BinaryNode<T> | null;
+    right: BinaryNode<T> | null;
+};
+
+export const tree: BinaryNode<number> = {
+    value: 20,
+    right: {
+        value: 50,
+        right: {
+            value: 100,
+            right: null,
+            left: null,
+        },
+        left: {
+            value: 30,
+            right: {
+                value: 45,
+                right: null,
+                left: null,
+            },
+            left: {
+                value: 29,
+                right: null,
+                left: null,
+            }
+        },
+    },
+    left: {
+        value: 10,
+        right: {
+            value: 15,
+            right: null,
+            left: null,
+        },
+        left: {
+            value: 5,
+            right: {
+                value: 7,
+                right: null,
+                left: null,
+            },
+            left: null,
+        }
+    }
+};

ts/tree_traversal.test.ts

@@ -0,0 +1,44 @@
+import { tree } from "./tree"
+
+type BinaryNode<T> = {
+    value: T;
+    left: BinaryNode<T> | null;
+    right: BinaryNode<T> | null;
+};
+
+// pre order 
+function walk(current: BinaryNode<number> | null, path: number[]): number[] {
+    if (!current) {
+        return path;
+    }
+
+    path.push(current.value);
+    walk(current.left, path);
+    walk(current.right, path);
+
+    return path;
+
+}
+
+function pre_order_search(head: BinaryNode<number>): number[] {
+    const path: number[] = [];
+    walk(head, path);
+
+    return path;
+
+}
+
+test("Pre order", function () {
+    expect(pre_order_search(tree)).toEqual([
+        20,
+        10,
+        5,
+        7,
+        15,
+        50,
+        30,
+        29,
+        45,
+        100,
+    ]);
+});