154 lines
4.1 KiB
Dart
154 lines
4.1 KiB
Dart
class SearchHeap<K, T> {
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final K Function(T) getKey;
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final int Function(T) getPriority;
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List<(T, K, int)> _items;
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Map<K, int> _indexByKey;
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SearchHeap({
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required this.getKey,
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required this.getPriority,
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}):
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_items = [],
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_indexByKey = {};
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factory SearchHeap.fromItems(
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List<T> items,
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{
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required K Function(T) getKey,
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required int Function(T) getPriority,
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}
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) {
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SearchHeap<K, T> heap = SearchHeap(getKey: getKey, getPriority: getPriority);
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for (final T item in items) {
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heap.add(item);
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}
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return heap;
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}
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T get first => _items.first.$1;
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T? get firstOrNull => _items.firstOrNull?.$1;
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int get length => _items.length;
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bool get isEmpty => _items.isEmpty;
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bool get isNotEmpty => _items.isNotEmpty;
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void add(T item) {
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final (T, K, int) heapItem = (item, getKey(item), getPriority(item));
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final int thisKey = heapItem.$3;
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int i = _items.length;
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_items.add(heapItem);
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while (i > 0 && _items[(i-1) >> 1].$3 > thisKey) {
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_items[i] = _items[(i-1) >> 1];
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_indexByKey[_items[i].$2] = i;
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i = (i-1) >> 1;
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}
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_items[i] = heapItem;
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_indexByKey[heapItem.$2] = i;
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}
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T removeFirst() {
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if (_items.isEmpty) {
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throw StateError("No element");
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}
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final T firstItem = _items[0].$1;
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_indexByKey.remove(_items[0].$2);
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if (_items.length < 2) {
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_items.length--;
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return firstItem;
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}
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final (T, K, int) itemToMove = _items.last;
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_items.length--;
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int i = 0;
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int leftIndex, rightIndex;
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bool stop = false;
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while (!stop) {
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rightIndex = (i+1) << 1;
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leftIndex = rightIndex-1;
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if (leftIndex < _items.length && itemToMove.$3 > _items[leftIndex].$3) {
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if (rightIndex < _items.length && _items[leftIndex].$3 > _items[rightIndex].$3) {
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_items[i] = _items[rightIndex];
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_indexByKey[_items[i].$2] = i;
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i = rightIndex;
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} else {
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_items[i] = _items[leftIndex];
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_indexByKey[_items[i].$2] = i;
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i = leftIndex;
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}
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} else if (rightIndex < _items.length && itemToMove.$3 > _items[rightIndex].$3) {
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_items[i] = _items[rightIndex];
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_indexByKey[_items[i].$2] = i;
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i = rightIndex;
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} else {
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stop = true;
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}
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}
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_items[i] = itemToMove;
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_indexByKey[itemToMove.$2] = i;
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return firstItem;
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}
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void updateElement(K key) {
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int i = _indexByKey[key]!;
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final (T, K, int) item = (_items[i].$1, _items[i].$2, getPriority(_items[i].$1));
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bool dontBubbleDown = false;
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while (i > 0 && _items[(i-1) >> 1].$3 > item.$3) {
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dontBubbleDown = true;
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_items[i] = _items[(i-1) >> 1];
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_indexByKey[_items[i].$2] = i;
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i = (i-1) >> 1;
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}
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int leftIndex, rightIndex;
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while (!dontBubbleDown) {
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rightIndex = (i+1) << 1;
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leftIndex = rightIndex-1;
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if (leftIndex < _items.length && item.$3 > _items[leftIndex].$3) {
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if (rightIndex < _items.length && _items[leftIndex].$3 > _items[rightIndex].$3) {
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_items[i] = _items[rightIndex];
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_indexByKey[_items[i].$2] = i;
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i = rightIndex;
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} else {
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_items[i] = _items[leftIndex];
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_indexByKey[_items[i].$2] = i;
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i = leftIndex;
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}
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} else if (rightIndex < _items.length && item.$3 > _items[rightIndex].$3) {
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_items[i] = _items[rightIndex];
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_indexByKey[_items[i].$2] = i;
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i = rightIndex;
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} else {
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dontBubbleDown = true;
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}
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}
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_items[i] = item;
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_indexByKey[item.$2] = i;
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}
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@override
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String toString() => _items.map(((T, K, int) item) => item.$1).toString();
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List<T> get debugItems => _items.map(((T, K, int) item) => item.$1).toList();
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Map<K, int> get debugPositionByKey => _indexByKey;
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bool get debugHeapValidity {
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for (int i = 1; i < _items.length; i++) {
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if (_items[i].$3 < _items[(i-1) >> 1].$3) {
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return false;
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}
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}
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return true;
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}
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bool get debugDictionaryValidity {
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for (final MapEntry<K, int>(key: K key, value: int index) in _indexByKey.entries) {
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if (_items[index].$2 != key) {
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return false;
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}
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}
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return true;
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}
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} |