delete method

void delete(K key)

Removes the entry with the given key.

Uses a swap-with-last strategy to maintain O(1) deletion:

1. Swaps the element to delete with the last element
2. Updates the map for the swapped element
3. Removes the last element from the list

If the key doesn't exist, this operation is a no-op.

Time complexity: O(1)

Example:

final map = FastMap<String, int>();
map.set('a', 1);
map.set('b', 2);
map.delete('a'); // Swaps 'a' with 'b', then removes last

Implementation

void delete(K key) {
  if (!_keyToIndex.containsKey(key)) return;

  final indexToDelete = _keyToIndex[key]!;
  final lastIndex = _values.length - 1;

  if (indexToDelete != lastIndex) {
    // Swap with last element
    _values[indexToDelete] = _values[lastIndex];

    // Update the map for the swapped element
    final swappedKey = _keyToIndex.entries
        .firstWhere((entry) => entry.value == lastIndex)
        .key;
    _keyToIndex[swappedKey] = indexToDelete;
  }

  // Remove the last element and the key
  _values.removeLast();
  _keyToIndex.remove(key);
}