diff --git a/a3/binary_search_tree.c b/a3/binary_search_tree.c
new file mode 100644
index 0000000..5a6ce53
--- /dev/null
+++ b/a3/binary_search_tree.c
@@ -0,0 +1,73 @@
+#include "binary_search_tree.h"
+#include <stdlib.h>
+
+node_t *build_tree(int *tree_data, size_t tree_data_len) {
+    if (tree_data_len == 0) {
+        return NULL;
+    }
+
+    node_t *root = malloc(sizeof(node_t));
+    root->data = tree_data[0];
+    root->left = NULL;
+    root->right = NULL;
+
+    for (size_t i = 1; i < tree_data_len; i++) {
+        node_t *current = root;
+        node_t *parent = NULL;
+
+        while (current!= NULL) {
+            parent = current;
+            if (tree_data[i] < current->data) {
+                current = current->left;
+            } else {
+                current = current->right;
+            }
+        }
+
+        current = malloc(sizeof(node_t));
+        current->data = tree_data[i];
+        current->left = NULL;
+        current->right = NULL;
+
+        if (tree_data[i] < parent->data) {
+            parent->left = current;
+        } else {
+            parent->right = current;
+        }
+    }
+
+    return root;
+}
+
+void free_tree(node_t *tree) {
+    if (tree == NULL) {
+        return;
+    }
+
+    free_tree(tree->left);
+    free_tree(tree->right);
+    free(tree);
+}
+
+int *sorted_data(node_t *tree) {
+    int *data = NULL;
+    size_t data_len = 0;
+
+    void in_order_traversal(node_t *node) {
+        if (node == NULL) {
+            return;
+        }
+
+        in_order_traversal(node->left);
+
+        data = realloc(data, (data_len + 1) * sizeof(int));
+        data[data_len] = node->data;
+        data_len++;
+
+        in_order_traversal(node->right);
+    }
+
+    in_order_traversal(tree);
+
+    return data;
+}
\ No newline at end of file