提交 ad61d062 编写于 作者: dengyihao's avatar dengyihao

add priority queue

上级 4a883c23
/*
* Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
*
* This program is free software: you can use, redistribute, and/or modify
* it under the terms of the GNU Affero General Public License, version 3
* or later ("AGPL"), as published by the Free Software Foundation.
*
* This program 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.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef TDENGINE_HEAP_H
#define TDENGINE_HEAP_H
#ifdef __cplusplus
extern "C" {
#endif
#include "os.h"
struct HeapNode;
/* Return non-zero if a < b. */
typedef int (*HeapCompareFn)(const struct HeapNode* a, const struct HeapNode* b);
typedef struct HeapNode {
struct HeapNode* left;
struct HeapNode* right;
struct HeapNode* parent;
} HeapNode;
/* A binary min heap. The usual properties hold: the root is the lowest
* element in the set, the height of the tree is at most log2(nodes) and
* it's always a complete binary tree.
*
*/
typedef struct {
HeapNode* min;
size_t nelts;
HeapCompareFn compFn;
} Heap;
Heap* heapCreate(HeapCompareFn fn);
void heapDestroy(Heap *heap);
HeapNode* heapMin(const Heap* heap);
void heapInsert(Heap* heap, HeapNode* node);
void heapRemove(Heap* heap, struct HeapNode* node);
void heapDequeue(Heap* heap);
size_t heapSize(Heap *heap);
#ifdef __cplusplus
}
#endif
#endif // TDENGINE_HASH_H
/*
* Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
*
* This program is free software: you can use, redistribute, and/or modify
* it under the terms of the GNU Affero General Public License, version 3
* or later ("AGPL"), as published by the Free Software Foundation.
*
* This program 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.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "theap.h"
size_t heapSize(Heap* heap) {
return heap->nelts;
}
Heap* heapCreate(HeapCompareFn fn) {
Heap *heap = calloc(1, sizeof(Heap));
if (heap == NULL) { return NULL; }
heap->min = NULL;
heap->nelts = 0;
heap->compFn = fn;
return heap;
}
void heapDestroy(Heap *heap) {
free(heap);
}
HeapNode* heapMin(const Heap* heap) {
return heap->min;
}
/* Swap parent with child. Child moves closer to the root, parent moves away. */
static void heapNodeSwap(Heap* heap, HeapNode* parent, HeapNode* child) {
HeapNode* sibling;
HeapNode t;
t = *parent;
*parent = *child;
*child = t;
parent->parent = child;
if (child->left == child) {
child->left = parent;
sibling = child->right;
} else {
child->right = parent;
sibling = child->left;
}
if (sibling != NULL)
sibling->parent = child;
if (parent->left != NULL)
parent->left->parent = parent;
if (parent->right != NULL)
parent->right->parent = parent;
if (child->parent == NULL)
heap->min = child;
else if (child->parent->left == parent)
child->parent->left = child;
else
child->parent->right = child;
}
void heapInsert(Heap* heap, HeapNode* newnode) {
HeapNode** parent;
HeapNode** child;
unsigned int path;
unsigned int n;
unsigned int k;
newnode->left = NULL;
newnode->right = NULL;
newnode->parent = NULL;
/* Calculate the path from the root to the insertion point. This is a min
* heap so we always insert at the left-most free node of the bottom row.
*/
path = 0;
for (k = 0, n = 1 + heap->nelts; n >= 2; k += 1, n /= 2)
path = (path << 1) | (n & 1);
/* Now traverse the heap using the path we calculated in the previous step. */
parent = child = &heap->min;
while (k > 0) {
parent = child;
if (path & 1)
child = &(*child)->right;
else
child = &(*child)->left;
path >>= 1;
k -= 1;
}
/* Insert the new node. */
newnode->parent = *parent;
*child = newnode;
heap->nelts += 1;
/* Walk up the tree and check at each node if the heap property holds.
* It's a min heap so parent < child must be true.
*/
while (newnode->parent != NULL && (heap->compFn)(newnode, newnode->parent))
heapNodeSwap(heap, newnode->parent, newnode);
}
void heapRemove(Heap* heap, HeapNode* node) {
HeapNode* smallest;
HeapNode** max;
HeapNode* child;
unsigned int path;
unsigned int k;
unsigned int n;
if (heap->nelts == 0)
return;
/* Calculate the path from the min (the root) to the max, the left-most node
* of the bottom row.
*/
path = 0;
for (k = 0, n = heap->nelts; n >= 2; k += 1, n /= 2)
path = (path << 1) | (n & 1);
/* Now traverse the heap using the path we calculated in the previous step. */
max = &heap->min;
while (k > 0) {
if (path & 1)
max = &(*max)->right;
else
max = &(*max)->left;
path >>= 1;
k -= 1;
}
heap->nelts -= 1;
/* Unlink the max node. */
child = *max;
*max = NULL;
if (child == node) {
/* We're removing either the max or the last node in the tree. */
if (child == heap->min) {
heap->min = NULL;
}
return;
}
/* Replace the to be deleted node with the max node. */
child->left = node->left;
child->right = node->right;
child->parent = node->parent;
if (child->left != NULL) {
child->left->parent = child;
}
if (child->right != NULL) {
child->right->parent = child;
}
if (node->parent == NULL) {
heap->min = child;
} else if (node->parent->left == node) {
node->parent->left = child;
} else {
node->parent->right = child;
}
/* Walk down the subtree and check at each node if the heap property holds.
* It's a min heap so parent < child must be true. If the parent is bigger,
* swap it with the smallest child.
*/
for (;;) {
smallest = child;
if (child->left != NULL && (heap->compFn)(child->left, smallest))
smallest = child->left;
if (child->right != NULL && (heap->compFn)(child->right, smallest))
smallest = child->right;
if (smallest == child)
break;
heapNodeSwap(heap, child, smallest);
}
/* Walk up the subtree and check that each parent is less than the node
* this is required, because `max` node is not guaranteed to be the
* actual maximum in tree
*/
while (child->parent != NULL && (heap->compFn)(child, child->parent))
heapNodeSwap(heap, child->parent, child);
}
void heapDequeue(Heap* heap) {
heapRemove(heap, heap->min);
}
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册