优先级队列(大顶堆)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MinPQsize 10
#define MaxData 32768
struct heapStruct
{
int capacity;
int size;
int *eles;
};

typedef struct heapStruct *priorityQueue;
priorityQueue initialize(int Maxelements)
{
priorityQueue H;
if (Maxelements < MinPQsize)
{
printf("Priority Queue size is too small");
exit(1);
}
H= (priorityQueue)malloc(sizeof(struct heapStruct));
if (H == NULL)
exit(1);

/* allocate the array plus one extra for sentinel */
H->eles = (int *)malloc((Maxelements + 1) * sizeof(int));
if (H->eles == NULL)
exit(1);

memset(H->eles, 0, (Maxelements + 1) * sizeof(int));

H->capacity = Maxelements;
H->size = 0;
H->eles[0] = MaxData;
return H;
}

bool isFull(priorityQueue H)
{
return H->size == H->capacity;
}

bool isEmpty(priorityQueue H)
{
return H->size == 0;
}

void destroy(priorityQueue H)
{
free(H->eles);
free(H);
}

/* H->eles[0] is a sentinel */

/* push heap */
/*    将最大值调整到第一个H->eles[1]     */
void insert(int X, priorityQueue H)
{
int i;
if (isFull(H))
{
printf("Priority queue is full");
exit(1);
}
for ( i = ++H->size; H->eles[i / 2] < X; i /= 2)
H->eles[i] = H->eles[i / 2];
H->eles[i] = X;
}

/* pop heap */
int deleteMax(priorityQueue H)
{
int i, child;
int MaxElement, LastElement;
if (isEmpty(H))
{
printf("priority queue is empty");
exit(1);
}

MaxElement = H->eles[1];
LastElement = H->eles[H->size--];

for (i = 1; i * 2 <= H->size; i = child)
{
/* find bigger child */
child = i * 2;
if (child != H->size - 1 && H->eles[child + 1] > H->eles[child])
child++;
/* precolate one level */
if (LastElement < H->eles[child])
H->eles[i] = H->eles[child];
else
break;
}
H->eles[i] = LastElement;
return MaxElement;
}

#define leftChild(i) (2*(i) + 1)
void percolate(int *arr, int i, int N)
{
int tmp, child;

for (tmp = arr[i]; leftChild(i) < N; i = child)
{
child = leftChild(i);
if (child != N - 1 && arr[child + 1] > arr[child])
child++;

if (arr[child] > tmp)
arr[i] = arr[child];
else
break;
}

arr[i] = tmp;
}

// 将一段现有数据转化为一个heap
void make_heap(int *arr, int N)
{
for (int i = N / 2; i >= 0; i--)
percolate(arr, i, N);
}

int main(void)
{
int arr[] = {3, 2, 1, 4, 5, 6, 7, 16, 15, 14, 13, 12, 11, 10, 8, 9};
priorityQueue T = NULL;

T = initialize(20);
int i;

for (i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
insert(arr[i], T);

for (i = sizeof(arr) / sizeof(arr[0]); i > 0; i--)
arr[i - 1] = deleteMax(T); //不断对heap进行pop操作，便可达到排序效果sort_heap

for (i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
printf("%d ", arr[i]);
printf("\n");
int arr2[] = {15, 2, 7, 20, 32, 28, 18, 34};
make_heap(arr2, sizeof(arr2) / sizeof(arr2[0]));
for (i = 0; i < sizeof(arr2) / sizeof(arr2[0]); i++)
printf("%d ", arr2[i]);
return 0;
}