算法导论 第六章 堆排序

#include <iostream>
using namespace std;
//修正i的位置，在此处已经假设i的子节点都是堆
void max_heapify(int* &a, int i, int length);
//建立数组的堆
void build_max_heap(int* &a, int length);
//利用堆对数组重新排序，总是拿第一个和最后一个对调，数组长度减一
void heap_sort(int* &a, int length);
//删除ith元素
void heap_delete(int* &a, int i, int length);
//插入x
void heap_insert(int* &a, int x, int length);
//将ith位置上的数增加到key
void increase_key(int* &a, int i, int key);
int main()
{
const int LEN = 10;
int b[10] = {12, 43, 0, -4, 98, 75, 64, 88, 5, 32};
int* a = new int[LEN];
for(int i = 0; i < LEN; i++)
a[i] = b[i];
build_max_heap(a, LEN);
increase_key(a, 7, 100);
heap_insert(a, 10, LEN);
heap_delete(a, 1, LEN);
heap_sort(a, LEN);
for(int i = 0; i < LEN; i++)
cout<<a[i]<<endl;
return 0;
}
void max_heapify(int* &a, int i, int length)
{
int largest = i;
while(largest <= length - 1)
{
int left = 2*largest + 1;
int right = 2*largest + 2;
int temp = largest;
if(left <= length - 1 && a[left] > a[largest])
{
largest = left;
}
if(right <= length - 1 && a[right] > a[largest])
{
largest = right;
}
if(largest != temp)
{
int exchange = a[largest];
a[largest] = a[temp];
a[temp] = exchange;
}
else
break;
}
}
void build_max_heap(int* &a, int length)
{
int root = length/2 - 1;
for(int i = root; i >= 0; i--)
max_heapify(a, i, length);
}
void heap_sort(int* &a, int length)
{
for(int i = length - 1; i >= 1; i--)
{
int temp = a[0];
a[0] = a[i];
a[i] = temp;
max_heapify(a, 0, i);
}
}
void heap_delete(int* &a, int i, int length)
{
if(i != length - 1)
{
a[i] = a[length - 1];
max_heapify(a, i, length);
}
}
void heap_insert(int* &a, int x, int length)
{
int* temp = a;
a = new int[length + 1];
for(int i = 0; i < length; i++)
a[i] = temp[i];
delete temp;
//用-10000000代替负无穷
a[length] = -10000000;
increase_key(a, length, x);
}
void increase_key(int* &a, int i, int key)
{
if(a[i] > key)
cout<<"key should be larger than a[i]"<<endl;
else
{
int parent = (i - 1)/2;
a[i] = key;
while(parent >= 0 && a[parent] < key)
{
int temp = a[parent];
a[parent] = key;
a[i] = temp;
i = parent;
parent = (i - 1)/2;
}
}
}