746dddc067
* Map is unnecessary and inefficient in almost every case. * Replaced by the new HashMap. * Renamed Map to RBMap and Set to RBSet for cases that still make sense (order matters) but use is discouraged. There were very few cases where replacing by HashMap was undesired because keeping the key order was intended. I tried to keep those (as RBMap) as much as possible, but might have missed some. Review appreciated!
150 lines
5.2 KiB
C++
150 lines
5.2 KiB
C++
/*************************************************************************/
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/* disjoint_set.h */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md). */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#ifndef DISJOINT_SET_H
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#define DISJOINT_SET_H
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#include "core/templates/rb_map.h"
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#include "core/templates/vector.h"
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/* This DisjointSet class uses Find with path compression and Union by rank */
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template <typename T, class H = HashMapHasherDefault, class C = HashMapComparatorDefault<T>, class AL = DefaultAllocator>
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class DisjointSet {
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struct Element {
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T object;
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Element *parent = nullptr;
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int rank = 0;
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};
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typedef HashMap<T, Element *, H, C> MapT;
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MapT elements;
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Element *get_parent(Element *element);
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_FORCE_INLINE_ Element *insert_or_get(T object);
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public:
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~DisjointSet();
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_FORCE_INLINE_ void insert(T object) { (void)insert_or_get(object); }
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void create_union(T a, T b);
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void get_representatives(Vector<T> &out_roots);
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void get_members(Vector<T> &out_members, T representative);
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};
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/* FUNCTIONS */
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template <typename T, class H, class C, class AL>
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DisjointSet<T, H, C, AL>::~DisjointSet() {
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for (KeyValue<T, Element *> &E : elements) {
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memdelete_allocator<Element, AL>(E.value);
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}
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}
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template <typename T, class H, class C, class AL>
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typename DisjointSet<T, H, C, AL>::Element *DisjointSet<T, H, C, AL>::get_parent(Element *element) {
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if (element->parent != element) {
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element->parent = get_parent(element->parent);
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}
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return element->parent;
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}
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template <typename T, class H, class C, class AL>
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typename DisjointSet<T, H, C, AL>::Element *DisjointSet<T, H, C, AL>::insert_or_get(T object) {
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typename MapT::Iterator itr = elements.find(object);
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if (itr != nullptr) {
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return itr->value;
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}
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Element *new_element = memnew_allocator(Element, AL);
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new_element->object = object;
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new_element->parent = new_element;
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elements.insert(object, new_element);
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return new_element;
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}
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template <typename T, class H, class C, class AL>
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void DisjointSet<T, H, C, AL>::create_union(T a, T b) {
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Element *x = insert_or_get(a);
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Element *y = insert_or_get(b);
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Element *x_root = get_parent(x);
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Element *y_root = get_parent(y);
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// Already in the same set
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if (x_root == y_root) {
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return;
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}
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// Not in the same set, merge
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if (x_root->rank < y_root->rank) {
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SWAP(x_root, y_root);
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}
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// Merge y_root into x_root
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y_root->parent = x_root;
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if (x_root->rank == y_root->rank) {
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++x_root->rank;
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}
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}
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template <typename T, class H, class C, class AL>
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void DisjointSet<T, H, C, AL>::get_representatives(Vector<T> &out_representatives) {
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for (KeyValue<T, Element *> &E : elements) {
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Element *element = E.value;
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if (element->parent == element) {
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out_representatives.push_back(element->object);
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}
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}
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}
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template <typename T, class H, class C, class AL>
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void DisjointSet<T, H, C, AL>::get_members(Vector<T> &out_members, T representative) {
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typename MapT::Iterator rep_itr = elements.find(representative);
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ERR_FAIL_COND(rep_itr == nullptr);
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Element *rep_element = rep_itr->value;
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ERR_FAIL_COND(rep_element->parent != rep_element);
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for (KeyValue<T, Element *> &E : elements) {
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Element *parent = get_parent(E.value);
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if (parent == rep_element) {
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out_members.push_back(E.key);
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}
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}
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}
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#endif // DISJOINT_SET_H
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