堆,是一种完全二叉树。而且在这颗树中,父节点必然大于(对于小顶堆为小于)子节点。
关于树的概念不了解可以看这里:http://www.cnblogs.com/HongYi-Liang/p/7231440.html
由于堆是一种完全二叉树,很适合保存为数组的形式。如下图示意的堆,红色数字为数组索引,黑色数字为数组的值,那么这个堆保存为数组的形式:heap={9,8,5,6,7,1,4,0,3,2};
值得注意的是,在堆中,若设父亲的索引为i,左儿子的索引刚好等于2i,而右儿子的索引等于2i+1。这个公式会大量地出现在下边的程序中。
关键概念:
大顶堆:树根元素为最大值往叶子递减,(父节点总是大于子节点)
小顶堆:树根元素为最小值往叶子递增,(父节点总是小于子节点)
下为一个大顶堆的示意图,父节点总是大于子节点
在下面的程序中,C将以大顶堆的形式编写,C++以小顶堆的形式编写。
C语言
程序源码:
本例子为大顶堆,包含4个文件(如下图)
MaxHeap.c
#include "MaxHeap.h"
bool MaxHeapConstructByBuffer(MaxHeap *heap,MAXHEAP_ELEM buff[],int length);
bool MaxHeapDesturct(MaxHeap *heap);
bool MaxHeap_getSize(MaxHeap *heap);
bool MaxHeap_isFull(MaxHeap *heap);
bool MaxHeap_isEmpty(MaxHeap *heap);
void MaxHeap_swap(MAXHEAP_ELEM *a,MAXHEAP_ELEM *b);
void MaxHeap_floating(MaxHeap *heap,int index);
void MaxHeap_sink(MaxHeap *heap, int index);
bool MaxHeap_push(MaxHeap *heap,MAXHEAP_ELEM data);
bool MaxHeap_push(MaxHeap *heap,MAXHEAP_ELEM data);
bool MaxHeap_pop(MaxHeap *heap,int index);
void MaxHeap_printfAll(MaxHeap *heap);
bool MaxHeapConstructByBuffer(MaxHeap *heap,MAXHEAP_ELEM buff[],int length)
{
int i;
if(NULL != heap->iDatas)
{
return false;
}
heap->iHeapCapacity=length;
heap->iHeapSize=0;
heap->iDatas = (MAXHEAP_ELEM*)malloc(sizeof(MAXHEAP_ELEM)*length);
for(i=0;i<length;i++)
{
MaxHeap_push(heap,buff[i]);
}
return true;
}
bool MaxHeapDesturct(MaxHeap *heap)
{
if(NULL == heap->iDatas)
{
return false;
}
free(heap->iDatas);
return true;
}
bool MaxHeap_getSize(MaxHeap *heap)
{
return heap->iHeapSize;
}
bool MaxHeap_isFull(MaxHeap *heap)
{
if(heap->iHeapCapacity == heap->iHeapSize)
{
return true;
}
return false;
}
bool MaxHeap_isEmpty(MaxHeap *heap)
{
if(0 == heap->iHeapSize)
{
return true;
}
return false;
}
void MaxHeap_swap(MAXHEAP_ELEM *a,MAXHEAP_ELEM *b)
{
MAXHEAP_ELEM temp;
temp=*a;
*a=*b;
*b=temp;
}
void MaxHeap_floating(MaxHeap *heap,int index)
{
int i;
for(i=index;i>0;i=(int)(i*0.5))
{
if(heap->iDatas[i-1] > heap->iDatas[(int)(i*0.5-1)] )
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[(int)(i*0.5-1)]);
}
else
{
break;
}
}
}
void MaxHeap_sink(MaxHeap *heap, int index)
{
int i=index;
while(i*2<=heap->iHeapSize)
{
if(heap->iDatas[i-1] < heap->iDatas[i*2-1])//it compare to left child
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[i*2-1]);
if(i*2+1<=heap->iHeapSize && heap->iDatas[i-1] < heap->iDatas[i*2])//it compare to right child
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[i*2]);
}
/*index*/
i=i*2;
}
else if(i*2+1<=heap->iHeapSize && heap->iDatas[i-1] < heap->iDatas[i*2])//it compare to right child
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[i*2]);
i=i*2+1;
}
else
{
break;
}
}
}
bool MaxHeap_push(MaxHeap *heap,MAXHEAP_ELEM data)
{
if( MaxHeap_isFull(heap))
return false;
heap->iDatas[heap->iHeapSize]=data;
heap->iHeapSize++;
MaxHeap_floating(heap,heap->iHeapSize);
return true;
}
bool MaxHeap_pop(MaxHeap *heap,int index)
{
if(MaxHeap_isEmpty(heap))
return false;
heap->iDatas[index]=heap->iDatas[heap->iHeapSize-1];
heap->iHeapSize--;
MaxHeap_sink(heap,index+1);
return true;
}
void MaxHeap_printfAll(MaxHeap *heap)
{
int i;
printf("heap:");
for( i=0;i<heap->iHeapSize;i++)
{
printf("%d ",heap->iDatas[i]);
}
printf("\r\n");
}
MaxHeap.h
#ifndef __MAXHEAP_H
#define __MAXHEAP_H
#include <stdlib.h>
#include <stdio.h>
#include "Mystdbool.h"
typedef int MAXHEAP_ELEM;
typedef struct
{
int iHeapCapacity;
int iHeapSize;
MAXHEAP_ELEM *iDatas;
}MaxHeap;
bool MaxHeapConstructByBuffer(MaxHeap *heap,MAXHEAP_ELEM buff[],int length);
bool MaxHeapDesturct(MaxHeap *heap);
bool MaxHeap_getSize(MaxHeap *heap);
bool MaxHeap_isFull(MaxHeap *heap);
bool MaxHeap_isEmpty(MaxHeap *heap);
void MaxHeap_swap(MAXHEAP_ELEM *a,MAXHEAP_ELEM *b);
void MaxHeap_floating(MaxHeap *heap,int index);
void MaxHeap_sink(MaxHeap *heap, int index);
bool MaxHeap_push(MaxHeap *heap,MAXHEAP_ELEM data);
bool MaxHeap_push(MaxHeap *heap,MAXHEAP_ELEM data);
bool MaxHeap_pop(MaxHeap *heap,int index);
void MaxHeap_printfAll(MaxHeap *heap);
#endif
Mystdbool.h(仅用于声明布尔类)
#ifndef _MYSTDBOOL_H
#define _MYSTDBOOL_H
typedef enum Bool
{
false=0,
true,
}bool;
#endif
main.c
#include "MaxHeap.h"
int main()
{
/*int buffer[10]={9,8,7,6,5,4,3,2,1,0};*/
int buffer[10]={0,1,2,3,4,5,6,7,8,9};
MaxHeap heap={0};
MaxHeapConstructByBuffer(&heap,buffer,10);
MaxHeap_printfAll(&heap);
MaxHeap_pop(&heap,0);
MaxHeap_printfAll(&heap);
MaxHeap_pop(&heap,0);
MaxHeap_printfAll(&heap);
system("pause");
return 0;
}
运行结果:
源码详解:
上浮:floating(int index)
- 将堆第index个元素与它的父亲比较,若小于它的父亲,则与它父亲交换数值。
- 上述过程如果发生,则把它继续上浮。
void MaxHeap_floating(MaxHeap *heap,int index)
{
int i;
for(i=index;i>0;i=(int)(i*0.5))
{
if(heap->iDatas[i-1] > heap->iDatas[(int)(i*0.5-1)] )
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[(int)(i*0.5-1)]);
}
else
{
break;
}
}
}
添加元素:push(T data)
- 把元素添加到堆的最后。
- 并使用上浮方法把堆的最后一个元素上浮。
bool MaxHeap_push(MaxHeap *heap,MAXHEAP_ELEM data)
{
if( MaxHeap_isFull(heap))
return false;
heap->iDatas[heap->iHeapSize]=data;
heap->iHeapSize++;
MaxHeap_floating(heap,heap->iHeapSize);
return true;
}
构建堆:MaxHeapConstructByBuffer()
- 用malloc为数据申请空间。
- 一个一个地将buff中的数据push()到堆中。
bool MaxHeapConstructByBuffer(MaxHeap *heap,MAXHEAP_ELEM buff[],int length)
{
int i;
if(NULL != heap->iDatas)
{
return false;
}
heap->iHeapCapacity=length;
heap->iHeapSize=0;
heap->iDatas = (MAXHEAP_ELEM*)malloc(sizeof(MAXHEAP_ELEM)*length);
for(i=0;i<length;i++)
{
MaxHeap_push(heap,buff[i]);
}
return true;
}
下沉:
- 从根开始,用父节点与左子节点比较。若父节点大于左子,则交换它们的值
- 用父节点与右子节点比较。若父节点大于右子,则交换它们的值。
- 若上述情况发生了,则继续下沉,直到无法下沉为止。
void MaxHeap_sink(MaxHeap *heap, int index)
{
int i=index;
while(i*2<=heap->iHeapSize)
{
if(heap->iDatas[i-1] < heap->iDatas[i*2-1])//it compare to left child
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[i*2-1]);
if(i*2+1<=heap->iHeapSize && heap->iDatas[i-1] < heap->iDatas[i*2])//it compare to right child
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[i*2]);
}
/*index*/
i=i*2;
}
else if(i*2+1<=heap->iHeapSize && heap->iDatas[i-1] < heap->iDatas[i*2])//it compare to right child
{
MaxHeap_swap(&heap->iDatas[i-1],&heap->iDatas[i*2]);
i=i*2+1;
}
else
{
break;
}
}
}
删除元素:pop(int index)
- 把堆的第index个元素删除,并把堆的最后一个元素放到index处。
- 把堆的第index个元素下沉
bool MaxHeap_pop(MaxHeap *heap,int index)
{
if(MaxHeap_isEmpty(heap))
return false;
heap->iDatas[index]=heap->iDatas[heap->iHeapSize-1];
heap->iHeapSize--;
MaxHeap_sink(heap,index+1);
return true;
}
C++
程序源码:
本例子为小顶堆,包含2个文件(如下图)
MyMinHeap.h:
此文件中为小顶堆的类模板。
#ifndef __MYMINHEAP_H
#define __MYMINHEAP_H
#include <iostream>
#include <vector>
using namespace std;
template <typename T>
class MyMinHeap
{
public:
MyMinHeap(T buff[],int length);
MyMinHeap(int capacity);
virtual ~MyMinHeap();
int getSize();
bool isFull();
bool isEmpty();
void swap(vector<T> &vec,int i,int j);
void floating(int index);
void sink(int index);
bool push(T data);
bool pop(int index);
//transval
void printfAll();
private:
int m_iHeapCapacity;
int m_iHeapSize;
vector<T> m_vecData;
};
template <typename T>
MyMinHeap<T>::MyMinHeap(T buff[],int length)
{
m_iHeapCapacity=length;
m_iHeapSize=0;
m_vecData.resize(length);
for(int i=0;i<length;i++)
{
push(buff[i]);
}
}
template <typename T>
MyMinHeap<T>:: MyMinHeap(int capacity)
{
m_iHeapCapacity=capacity;
m_iHeapSize=0;
m_vecData.resize(capacity);
}
template <typename T>
MyMinHeap<T>::~MyMinHeap()
{
}
template <typename T>
int MyMinHeap<T>::getSize()
{
return m_iHeapSize;
}
template <typename T>
bool MyMinHeap<T>::isFull()
{
if(m_iHeapSize>=m_iHeapCapacity)
{
return true;
}
return false;
}
template <typename T>
bool MyMinHeap<T>::isEmpty()
{
if(m_iHeapSize==0)
return true;
return false;
}
template <typename T>
void MyMinHeap<T>::swap(vector<T> &vec,int i,int j)
{
T temp = vec[i];
vec[i]=vec[j];
vec[j]=temp;
}
template <typename T>
void MyMinHeap<T>::floating(int index)
{
T temp;
for(int i=index;i>0;i*=0.5)
{
if(m_vecData[i-1]<m_vecData[i*0.5-1] )
{
swap(m_vecData,i-1,i*0.5-1);
}
else
{
break;
}
}
}
template <typename T>
void MyMinHeap<T>::sink(int index)
{
int i=index;
while(i*2<=m_iHeapSize)
{
if(m_vecData[i-1]>m_vecData[i*2-1])//it compare to left child
{
swap(m_vecData,i-1,i*2-1);
if(i*2+1<=m_iHeapSize && m_vecData[i-1]>m_vecData[i*2])//it compare to right child
{
swap(m_vecData,i-1,i*2);
}
/*index*/
i=i*2;
}
else if(i*2+1<=m_iHeapSize && m_vecData[i-1]>m_vecData[i*2])//it compare to right child
{
swap(m_vecData,i-1,i*2);
i=i*2+1;
}
else
{
break;
}
}
}
template <typename T>
bool MyMinHeap<T>::push(T data)
{
if(isFull())
return false;
m_vecData[m_iHeapSize]=data;
m_iHeapSize++;
floating(m_iHeapSize);
return true;
}
template <typename T>
bool MyMinHeap<T>::pop(int index)
{
if(isEmpty())
return false;
m_vecData[index]=m_vecData[m_iHeapSize-1];
m_iHeapSize--;
sink(index+1);
return true;
}
template <typename T>
void MyMinHeap<T>::printfAll()
{
cout<<"heap:";
for(int i=0;i<m_iHeapSize;i++)
{
cout<<m_vecData[i]<<" ";
}
cout<<endl<<endl;
}
#endif
main.h:
主程序用于测试运行。
#include <iostream>
#include "MyMinHeap.h"
using namespace std;
int main()
{
int buffer[10]={9,8,7,6,5,4,3,2,1,0};
MyMinHeap<int> heap(buffer,10);
heap.printfAll();
heap.pop(1);
heap.printfAll();
heap.push(1);
heap.printfAll();
system("pause");
return 0;
}
运行结果:
源码详解:
上浮:floating(int index)
- 将堆第index个元素与它的父亲比较,若小于它的父亲,则与它父亲交换数值。
- 上述过程如果发生,则把它继续上浮。
template <typename T>
void MyMinHeap<T>::floating(int index)
{
T temp;
for(int i=index;i>0;i*=0.5)
{
if(m_vecData[i-1]<m_vecData[i*0.5-1] )
{
swap(m_vecData,i-1,i*0.5-1);
}
else
{
break;
}
}
}
添加元素:push(T data)
- 把元素添加到堆的最后。
- 并使用上浮方法把堆的最后一个元素上浮。
template <typename T>
bool MyMinHeap<T>::push(T data)
{
if(isFull())
return false;
m_vecData[m_iHeapSize]=data;
m_iHeapSize++;
floating(m_iHeapSize);
return true;
}
构造函数:使用数组构建堆:
连续使用push()把buff中所有元素一个一个地加入堆中。
template <typename T>
MyMinHeap<T>::MyMinHeap(T buff[],int length)
{
m_iHeapCapacity=length;
m_iHeapSize=0;
m_vecData.resize(length);
for(int i=0;i<length;i++)
{
push(buff[i]);
}
}
下沉:
- 从根开始,用父节点与左子节点比较。若父节点大于左子,则交换它们的值
- 用父节点与右子节点比较。若父节点大于右子,则交换它们的值。
- 若上述情况发生了,则继续下沉,直到无法下沉为止。
template <typename T>
void MyMinHeap<T>::sink(int index)
{
int i=index;
while(i*2<=m_iHeapSize)
{
if(m_vecData[i-1]>m_vecData[i*2-1])//it compare to left child
{
swap(m_vecData,i-1,i*2-1);
if(i*2+1<=m_iHeapSize && m_vecData[i-1]>m_vecData[i*2])//it compare to right child
{
swap(m_vecData,i-1,i*2);
}
/*index*/
i=i*2;
}
else if(i*2+1<=m_iHeapSize && m_vecData[i-1]>m_vecData[i*2])//it compare to right child
{
swap(m_vecData,i-1,i*2);
i=i*2+1;
}
else
{
break;
}
}
}
删除元素:pop(int index)
- 把堆的第index个元素删除,并把堆的最后一个元素放到index处。
- 把堆的第index个元素下沉
template <typename T>
bool MyMinHeap<T>::pop(int index)
{
if(isEmpty())
return false;
m_vecData[index]=m_vecData[m_iHeapSize-1];
m_iHeapSize--;
sink(index+1);
return true;
}