【数据结构】之用堆实现优先队列

#include <stdio.h>
#include <malloc.h>

/**
* 使用堆来实现优先队列
* 堆的最重要性质就是子节点的值>=父节点的值,
* 而且树的节点是从上到下、从左到右的顺序紧凑排列的
*/

//这里我封装了一个二叉树
typedef struct BinaryTree{
int *note;
int size;
void (*push)(struct BinaryTree* , int);
int (*pop)(struct BinaryTree* );
} BinaryTree;

/**
* 插入数值
* 大致思路:首先在二叉树末尾添加此数值,然后如果它比父节点小就向上提升,
* 直到不小于父节点或者已经移到根节点为止
*/
void tree_push(BinaryTree *this, int num){
int parent = (this->size-1) / 2;
int curIndex = this->size++;
while (num < this->note[parent] && curIndex > 0){
this->note[curIndex] = this->note[parent];
curIndex = parent;
parent
e12d
= (parent-1) / 2;
}
this->note[curIndex] = num;
}

/**
* 删除最小值
* 大致思路:根节点就是最小值,把末尾的值赋在根节点上,然后删除末尾节点,
* 然后不断向下交换直到没有大小颠倒为止,向下交换中,如果有两个子节点,
* 则选择数值较小的子节点与其进行交换
*/
int tree_pop(BinaryTree *this){
//最小值
int ret = this->note[0];
//末尾的元素
int x = this->note[--this->size];
int curIndex = 0;
int a = curIndex * 2 + 1, b = curIndex * 2 + 2;
while (x > this->note[a] && a < this->size){
if (this->note[a] > this->note && b < this->size)
a = b;
this->note[curIndex] = this->note[a];
curIndex = a;
a = curIndex * 2 + 1, b = curIndex * 2 + 2;
}
this->note[curIndex] = x;
[b]return ret;
}

//初始化
BinaryTree * new_BinaryTree(int max_size){
BinaryTree *tree = malloc(sizeof(BinaryTree));
tree->note = malloc(sizeof(int) * max_size);
tree->size = 0;
tree->pop = tree_pop;
tree->push = tree_push;
return tree;
}

//测试代码
int main() {
BinaryTree *tree = new_BinaryTree(1000);
tree->push(tree, 3);
tree->push(tree, 1);
tree->push(tree, 0);
tree->push(tree, 2);
tree->push(tree, 2);
tree->push(tree, 1);
tree->push(tree, 0);
tree->push(tree, -1);
for (int i = 0; i < tree->size; ++i) {
printf("%d ",tree->note[i]);
}
printf("\n");
tree->pop(tree);
for (int i = 0; i < tree->size; ++i) {
printf("%d ",tree->note[i]);
}

return 0;
}