remove inv duping

src/main.c

@@ -101,6 +101,15 @@ int main(int argc, char *argv[]) {
 
     char *res_str = (char *)result;
 
+    uintptr_t result2;
+
+    hashmap_get(inv, res_str, strlen(res_str), &result2);
+
+    if (result2 == 1) {
+      printf("You made %s, but you already have it.\n", res_str);
+      continue;
+    }
+
     hashmap_set(inv, res_str, strlen(res_str), (uintptr_t)1, 0);
     printf("You made %s!\n", res_str);