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ton/tdutils/td/utils/Heap.h
2019-09-07 14:33:36 +04:00

171 lines
3.6 KiB
C++

/*
This file is part of TON Blockchain Library.
TON Blockchain Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
TON Blockchain Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
Copyright 2017-2019 Telegram Systems LLP
*/
#pragma once
#include "td/utils/common.h"
namespace td {
struct HeapNode {
bool in_heap() const {
return pos_ != -1;
}
bool is_top() const {
return pos_ == 0;
}
void remove() {
pos_ = -1;
}
int pos_ = -1;
};
template <class KeyT, int K = 4>
class KHeap {
public:
bool empty() const {
return array_.empty();
}
size_t size() const {
return array_.size();
}
KeyT top_key() const {
return array_[0].key_;
}
HeapNode *pop() {
CHECK(!empty());
HeapNode *result = array_[0].node_;
result->remove();
erase(0);
return result;
}
void insert(KeyT key, HeapNode *node) {
CHECK(!node->in_heap());
array_.push_back({key, node});
fix_up(static_cast<int>(array_.size()) - 1);
}
void fix(KeyT key, HeapNode *node) {
CHECK(node->in_heap());
int pos = node->pos_;
KeyT old_key = array_[pos].key_;
array_[pos].key_ = key;
if (key < old_key) {
fix_up(pos);
} else {
fix_down(pos);
}
}
void erase(HeapNode *node) {
CHECK(node->in_heap());
int pos = node->pos_;
node->remove();
erase(pos);
}
template <class F>
void for_each(F &&f) const {
for (auto &it : array_) {
f(it.key_, it.node_);
}
}
template <class F>
void for_each(F &&f) {
for (auto &it : array_) {
f(it.key_, it.node_);
}
}
void check() const {
for (size_t i = 0; i < array_.size(); i++) {
for (size_t j = i * K + 1; j < i * K + 1 + K && j < array_.size(); j++) {
CHECK(array_[i].key_ <= array_[j].key_);
}
}
}
private:
struct Item {
KeyT key_;
HeapNode *node_;
};
vector<Item> array_;
void fix_up(int pos) {
auto item = array_[pos];
while (pos) {
int parent_pos = (pos - 1) / K;
auto parent_item = array_[parent_pos];
if (parent_item.key_ < item.key_) {
break;
}
parent_item.node_->pos_ = pos;
array_[pos] = parent_item;
pos = parent_pos;
}
item.node_->pos_ = pos;
array_[pos] = item;
}
void fix_down(int pos) {
auto item = array_[pos];
while (true) {
int left_pos = pos * K + 1;
int right_pos = min(left_pos + K, static_cast<int>(array_.size()));
int next_pos = pos;
KeyT next_key = item.key_;
for (int i = left_pos; i < right_pos; i++) {
KeyT i_key = array_[i].key_;
if (i_key < next_key) {
next_key = i_key;
next_pos = i;
}
}
if (next_pos == pos) {
break;
}
array_[pos] = array_[next_pos];
array_[pos].node_->pos_ = pos;
pos = next_pos;
}
item.node_->pos_ = pos;
array_[pos] = item;
}
void erase(int pos) {
array_[pos] = array_.back();
array_.pop_back();
if (pos < static_cast<int>(array_.size())) {
fix_down(pos);
fix_up(pos);
}
}
};
} // namespace td