C语言数据结构堆的基本操作实现

1.基本函数实现

a.代码1(向下调整)

void AdjustDown(DateType*a, int n, int parent)
{
	int child = parent * 2 + 1;
	while (child<n)
	{
		if ((child+1) < n && a[child] > a[child + 1])
		{
			++child;
		}
		if (a[parent] > a[child])
		{
			Swap(&a[parent], &a[child]);
			parent = child;
			child = parent * 2 + 1;
		}
		else
		{
			break;
		}
	}
}

注意:if里面的条件语句(child +1)<n是防止越界的,因为不能保证有右孩子。

b.代码2(向上调整)

void AdjustUp(DateType*a , int child)
{
	int parent = (child - 1) / 2;
	while (child > 0)
	{
		if (a[child] < a[parent])
		{
			Swap(&a[child], &a[parent]);
			child = parent;
			parent = (child - 1) / 2;
		}
		else
		{
			break;
		}
	}
}

注意:while里面的条件语句是不能够写成(parent<0),因为当child==0时,parent=(child - 1) / 2,parent==0,再次进入循环不满足a[child] < a[parent],恰好跳出循环。如果写成(a[child] <= a[parent])就死循环了

c.代码3(交换)

void Swap(DateType*p1, DateType*p2)
{
	DateType tmp = *p1;
	*p1 = *p2;
	*p2 = tmp;
}

2.建堆 

void CreatHeap(Heap*p,DateType*num,int n)
{
	assert(p);
	p->a = (DateType*)malloc(n * sizeof(DateType));
	if (p->a == NULL)
	{
		printf("malloc failed
");
		exit(-1);
	}
	memcpy(p->a, num, n * sizeof(DateType));
	p->size = n;
	p->capacity = n;
	//建小堆
	for (int i = (n - 1 - 1) / 2; i >= 0; i--)
	{
		AdjustDown(p->a, p->size, i);
	}
}

3.插入数据

void HeapPush(Heap*p, DateType x)
{
	assert(p);
	if (p->size == p->capacity)
	{
		DateType*tmp = (DateType*)realloc(p->a, (p->capacity) * 2 * sizeof(DateType));
		if (tmp == NULL)
		{
			printf("realloc  failed
 ");
			exit(-1);
		}
	}
	(p->capacity) *= 2;
	p->a[p->size] = x;
	++(p->size);
	//向上调整
	AdjustUp(p->a, p->size-1);
}

4. 删除数据

void HeapPop(Heap*p, DateType x)
{
	assert(p);
	Swap(&p->a[0], &p->a[p->size-1]);
	--(p->size);
	AdjustDown(p->a, p->size, 0);
	//左右子树还是小堆,直接调整行了
}

把堆顶的数据与最后一个数据交换,再次调整size-1个数据。 

5.获取堆顶的数据

DateType HeapTop(Heap*p)
{
	assert(p);
	return p->a[0];
}

6.堆的数据个数

int HeapSize(Heap*p)
{
	assert(p);
	return p->size;
}

7.判空

bool HeapIsEmpty(Heap*p)
{
	assert(p);
	return p->size == 0;
}

8.打印

void Print(Heap*p)
{
	assert(p);
	for (int i = 0; i < p->size; i++)
	{
		printf("%d ", (p->a)[i]);
	}
	printf("
");
	int count = 0;//计数
	int levelsize = 1;
	for (int i = 0; i < p->size; i++)
	{
		printf("%d ", p->a[i]);
		++count;
		if (count == levelsize)
		{
			printf("
");
			levelsize *= 2;
			count = 0;//重新计数
		}
	}
	printf("
");
}

9.销毁

void HeapDestory(Heap*p)
{
	assert(p);
	free(p->a);
	p->a = NULL;
	p->capacity = p->size = 0;
}

10.测试

int main()
{
	int num[] = { 12,15,17,23,10,25 };
	int n = sizeof(num) / sizeof(num[0]); 
	Heap a;
 	//创建小堆
	CreatHeap(&a,num, n);
	Print(&a);
	printf("
"); 
	//插入数据
	HeapPush(&a, 1);
	Print(&a);
 	//删除对顶的数据
	HeapPop(&a);
	Print(&a);
	printf("
"); 
	//获取堆顶数据
	int ret=HeapTop(&a);
	printf("The top date is %d
",ret); 
	//堆的数据个数
	int number=HeapSize(&a);
	printf("The number of heap is %d
", number); 
	//销毁
	HeapDestory(&a); 
	return 0;
}

11.测试结果

12.用堆排序(降序)

a.代码1

int main()
{
	DateType num[] = { 12,15,17,23,10,25 };
	int n = sizeof(num) / sizeof(num[0]);
	HeapSort(num, n);
	for (int i = 0; i < n; i++)
	{
		printf("%d ", num[i]);
	}
	printf("

");
	return 0;
}
 
void HeapSort(int*num, int n)
{
	//建小堆
	for (int i = (n - 1 - 1) / 2; i >= 0; i--)
	{
		AdjustDown(num, n, i);
	}
	int end = n - 1;
	while (end>0)
	{
		Swap(&num[0], &num[end]);
		AdjustDown(num, end, 0);
		--end;
	}
}

运行结果

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