adds ts for tree searches

c/hash-table-pro.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <string.h>
+
+typedef struct item {
+    char *key;
+    int   value;
+} item;
+
+item *linear_search(item *items, size_t size, const char *key) {
+    for (size_t i = 0; i < size; i++) {
+        if (strcmp(items[i].key, key) == 0) {
+            return (&items[i]);
+        }
+    }
+
+    return (NULL);
+}
+
+int main() {
+    item items[] = {
+        {"foo", 10},
+        {"bar", 20},
+        {"hello", 30},
+        {"x", 40}};
+
+    size_t total_items = sizeof(items) / sizeof(items);
+
+    item *found = linear_search(items, total_items, "foo");
+
+    if (found == NULL) {
+        printf("linear search: value of 'foo' has no key\n");
+        return (1);
+    }
+
+    printf("linear search: value of 'foo' is: %d", found->value);
+    return (0);
+}

c/hash-table.c

@@ -0,0 +1,136 @@
+#include <stdio.h>
+#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 {
+    Node *data[MAX_HASH_TABLE_SIZE];
+} HashTable;
+
+HashTable *new_hashtable() {
+    HashTable *ht = malloc(sizeof(HashTable));
+    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;
+    } else {
+        return -1;
+    }
+}
+
+int hash(char *word) {
+    int word_len = strlen(word);
+    int accum = 1;
+    int index;
+    for (int i = 0; i < word_len; i++) {
+        index = get_index_for_letter(word[i]);
+        accum *= index;
+    }
+
+    return accum % 16;
+}
+
+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);
+        }
+    }
+
+    return (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 *h = new_hashtable();
+
+    // 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,
+    ]);
+});