mirror of
https://github.com/SerenityOS/serenity
synced 2024-10-04 23:19:27 +00:00
AK: Implement minimum BinaryHeap
This enables efficient implementations of priority queues, and will also be used in LibCompress for efficient huffman tree generation.
This commit is contained in:
parent
0ddc0e45ae
commit
168cf6fac9
128
AK/BinaryHeap.h
Normal file
128
AK/BinaryHeap.h
Normal file
|
@ -0,0 +1,128 @@
|
||||||
|
/*
|
||||||
|
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
|
||||||
|
* All rights reserved.
|
||||||
|
*
|
||||||
|
* Redistribution and use in source and binary forms, with or without
|
||||||
|
* modification, are permitted provided that the following conditions are met:
|
||||||
|
*
|
||||||
|
* 1. Redistributions of source code must retain the above copyright notice, this
|
||||||
|
* list of conditions and the following disclaimer.
|
||||||
|
*
|
||||||
|
* 2. Redistributions in binary form must reproduce the above copyright notice,
|
||||||
|
* this list of conditions and the following disclaimer in the documentation
|
||||||
|
* and/or other materials provided with the distribution.
|
||||||
|
*
|
||||||
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||||||
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||||
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
||||||
|
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
||||||
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||||||
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
||||||
|
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
||||||
|
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
||||||
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||||
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#pragma once
|
||||||
|
|
||||||
|
namespace AK {
|
||||||
|
|
||||||
|
template<typename K, typename V, size_t Capacity>
|
||||||
|
class BinaryHeap {
|
||||||
|
public:
|
||||||
|
BinaryHeap() = default;
|
||||||
|
~BinaryHeap() = default;
|
||||||
|
|
||||||
|
// This constructor allows for O(n) construction of the heap (instead of O(nlogn) for repeated insertions)
|
||||||
|
BinaryHeap(K keys[], V values[], size_t size)
|
||||||
|
{
|
||||||
|
VERIFY(size <= Capacity);
|
||||||
|
m_size = size;
|
||||||
|
__builtin_memcpy(m_keys, keys, size * sizeof(K));
|
||||||
|
__builtin_memcpy(m_values, values, size * sizeof(V));
|
||||||
|
|
||||||
|
for (ssize_t i = size / 2; i >= 0; i--) {
|
||||||
|
heapify_down(i);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
[[nodiscard]] size_t size() const { return m_size; }
|
||||||
|
[[nodiscard]] bool is_empty() const { return m_size == 0; }
|
||||||
|
|
||||||
|
void insert(K key, V value)
|
||||||
|
{
|
||||||
|
VERIFY(m_size < Capacity);
|
||||||
|
auto index = m_size++;
|
||||||
|
m_keys[index] = key;
|
||||||
|
m_values[index] = value;
|
||||||
|
heapify_up(index);
|
||||||
|
}
|
||||||
|
|
||||||
|
V pop_min()
|
||||||
|
{
|
||||||
|
VERIFY(!is_empty());
|
||||||
|
auto index = --m_size;
|
||||||
|
swap(m_keys[0], m_keys[index]);
|
||||||
|
swap(m_values[0], m_values[index]);
|
||||||
|
heapify_down(0);
|
||||||
|
return m_values[index];
|
||||||
|
}
|
||||||
|
|
||||||
|
const V& peek_min() const
|
||||||
|
{
|
||||||
|
VERIFY(!is_empty());
|
||||||
|
return m_values[0];
|
||||||
|
}
|
||||||
|
|
||||||
|
const V& peek_min_key() const
|
||||||
|
{
|
||||||
|
VERIFY(!is_empty());
|
||||||
|
return m_keys[0];
|
||||||
|
}
|
||||||
|
|
||||||
|
void clear()
|
||||||
|
{
|
||||||
|
m_size = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
private:
|
||||||
|
void heapify_down(size_t index)
|
||||||
|
{
|
||||||
|
while (index * 2 + 1 < m_size) {
|
||||||
|
auto left_child = index * 2 + 1;
|
||||||
|
auto right_child = index * 2 + 2;
|
||||||
|
|
||||||
|
auto min_child = left_child;
|
||||||
|
if (right_child < m_size && m_keys[right_child] < m_keys[min_child])
|
||||||
|
min_child = right_child;
|
||||||
|
|
||||||
|
if (m_keys[index] <= m_keys[min_child])
|
||||||
|
break;
|
||||||
|
swap(m_keys[index], m_keys[min_child]);
|
||||||
|
swap(m_values[index], m_values[min_child]);
|
||||||
|
index = min_child;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
void heapify_up(size_t index)
|
||||||
|
{
|
||||||
|
while (index != 0) {
|
||||||
|
auto parent = (index - 1) / 2;
|
||||||
|
|
||||||
|
if (m_keys[index] >= m_keys[parent])
|
||||||
|
break;
|
||||||
|
swap(m_keys[index], m_keys[parent]);
|
||||||
|
swap(m_values[index], m_values[parent]);
|
||||||
|
index = parent;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
K m_keys[Capacity];
|
||||||
|
V m_values[Capacity];
|
||||||
|
size_t m_size { 0 };
|
||||||
|
};
|
||||||
|
|
||||||
|
}
|
||||||
|
|
||||||
|
using AK::BinaryHeap;
|
|
@ -7,6 +7,7 @@ set(AK_TEST_SOURCES
|
||||||
TestAtomic.cpp
|
TestAtomic.cpp
|
||||||
TestBadge.cpp
|
TestBadge.cpp
|
||||||
TestBase64.cpp
|
TestBase64.cpp
|
||||||
|
TestBinaryHeap.cpp
|
||||||
TestBinarySearch.cpp
|
TestBinarySearch.cpp
|
||||||
TestBitmap.cpp
|
TestBitmap.cpp
|
||||||
TestByteBuffer.cpp
|
TestByteBuffer.cpp
|
||||||
|
|
89
AK/Tests/TestBinaryHeap.cpp
Normal file
89
AK/Tests/TestBinaryHeap.cpp
Normal file
|
@ -0,0 +1,89 @@
|
||||||
|
/*
|
||||||
|
* Copyright (c) 2021, Idan Horowitz <idan.horowitz@gmail.com>
|
||||||
|
* All rights reserved.
|
||||||
|
*
|
||||||
|
* Redistribution and use in source and binary forms, with or without
|
||||||
|
* modification, are permitted provided that the following conditions are met:
|
||||||
|
*
|
||||||
|
* 1. Redistributions of source code must retain the above copyright notice, this
|
||||||
|
* list of conditions and the following disclaimer.
|
||||||
|
*
|
||||||
|
* 2. Redistributions in binary form must reproduce the above copyright notice,
|
||||||
|
* this list of conditions and the following disclaimer in the documentation
|
||||||
|
* and/or other materials provided with the distribution.
|
||||||
|
*
|
||||||
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||||||
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||||||
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
||||||
|
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
||||||
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||||||
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
||||||
|
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
||||||
|
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
||||||
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
||||||
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||||||
|
*/
|
||||||
|
|
||||||
|
#include <AK/TestSuite.h>
|
||||||
|
|
||||||
|
#include <AK/BinaryHeap.h>
|
||||||
|
#include <AK/String.h>
|
||||||
|
|
||||||
|
TEST_CASE(construct)
|
||||||
|
{
|
||||||
|
BinaryHeap<int, int, 5> empty;
|
||||||
|
EXPECT(empty.is_empty());
|
||||||
|
EXPECT(empty.size() == 0);
|
||||||
|
}
|
||||||
|
|
||||||
|
TEST_CASE(construct_from_existing)
|
||||||
|
{
|
||||||
|
int keys[] = { 3, 2, 1 };
|
||||||
|
char values[] = { 'c', 'b', 'a' };
|
||||||
|
BinaryHeap<int, char, 5> from_existing(keys, values, 3);
|
||||||
|
EXPECT(from_existing.size() == 3);
|
||||||
|
EXPECT_EQ(from_existing.pop_min(), 'a');
|
||||||
|
EXPECT_EQ(from_existing.pop_min(), 'b');
|
||||||
|
EXPECT_EQ(from_existing.pop_min(), 'c');
|
||||||
|
}
|
||||||
|
|
||||||
|
TEST_CASE(populate_int)
|
||||||
|
{
|
||||||
|
BinaryHeap<int, int, 5> ints;
|
||||||
|
ints.insert(1, 10);
|
||||||
|
ints.insert(3, 20);
|
||||||
|
ints.insert(2, 30);
|
||||||
|
EXPECT_EQ(ints.size(), 3u);
|
||||||
|
EXPECT_EQ(ints.pop_min(), 10);
|
||||||
|
EXPECT_EQ(ints.size(), 2u);
|
||||||
|
EXPECT_EQ(ints.pop_min(), 30);
|
||||||
|
EXPECT_EQ(ints.size(), 1u);
|
||||||
|
EXPECT_EQ(ints.pop_min(), 20);
|
||||||
|
EXPECT_EQ(ints.size(), 0u);
|
||||||
|
}
|
||||||
|
|
||||||
|
TEST_CASE(populate_string)
|
||||||
|
{
|
||||||
|
BinaryHeap<int, String, 5> strings;
|
||||||
|
strings.insert(1, "ABC");
|
||||||
|
strings.insert(2, "DEF");
|
||||||
|
EXPECT_EQ(strings.size(), 2u);
|
||||||
|
EXPECT_EQ(strings.pop_min(), "ABC");
|
||||||
|
EXPECT_EQ(strings.pop_min(), "DEF");
|
||||||
|
EXPECT(strings.is_empty());
|
||||||
|
}
|
||||||
|
|
||||||
|
TEST_CASE(large_populate_reverse)
|
||||||
|
{
|
||||||
|
BinaryHeap<int, int, 1024> ints;
|
||||||
|
for (int i = 1023; i >= 0; i--) {
|
||||||
|
ints.insert(i, i);
|
||||||
|
}
|
||||||
|
EXPECT_EQ(ints.size(), 1024u);
|
||||||
|
for (int i = 0; i < 1024; i++) {
|
||||||
|
EXPECT_EQ(ints.peek_min(), i);
|
||||||
|
EXPECT_EQ(ints.pop_min(), i);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
TEST_MAIN(BinaryHeap)
|
Loading…
Reference in a new issue