2.fc

{-

  TASK 2 - Merge hashmaps (dictionaries)
  Write the method that merges two hashmaps into one. When keys of hashmaps
  interesect - values from first hashmap should be used, while discarded
  key/value pairs should be stored into separate hashmap.
  Method should return two hashmaps (merged_dict, discared_dict). If any
  of resulting hashmaps is empty it should be represented by `null` value.
  Hashmap key length is 256 bit. Each hashmap has at most 256 elements.
-}

() recv_internal() impure {
}


;; testable
(cell, cell) merge_hashmaps(cell dict1, cell dict2) method_id {
    
    var (k1, k2) = (0,  0);
    var merged_dict = new_dict();
    var discarded_dict = new_dict();

    int key_len = 256;

    ;; Add all elements in first dictionary.
    var (k1, e1, succ1) = udict_get_next?(dict1, key_len, k1);
    while (succ1) {
      _ = merged_dict~udict_add?(key_len, k1, e1);
      (k1, e1, succ1) = udict_get_next?(dict1, key_len, k1);
    }

    ;; Try to add all elements in second dictionary, however, add the elements which has already been added from
    ;; first dictionary to discarded dictionary.
    var (k2, e2, succ2) = udict_get_next?(dict2, key_len, k2);
    while (succ2) {
      var added = merged_dict~udict_add?(key_len, k2, e2);

      ;; If the key-value pair is already exists, keep te value from dict1 and add the value from dict2 to discarded set.
      if (added == false) {
        discarded_dict~udict_add?(key_len, k2, e2);
      }

      (k2, e2, succ2) = udict_get_next?(dict2, key_len, k2);
    }

    return (merged_dict, discarded_dict);
}