C语言实现八种基本排序（三）

#include <stdio.h>
//the value of heapSize is belong 0 and (length - 1).
int heapSize = 0;
//get the left index of parent
int Left(int parent)
{
return ((parent << 1) + 1);
}
//get the right index of parent
int Right(int parent)
{
return ((parent << 1) + 2);
}
//exchange the two values
void swap(int *a, int *b)
{
*a ^= *b;
*b ^= *a;
*a ^= *b;
}
//modify the heap and sign that the children of array[index] have been maxheaps.
void maxHeapify(int *array, int parent)
{
int largest = parent;
int left = Left(parent);
int right = Right(parent);
if((left <= heapSize) && (array[left] > array[largest]))
largest = left;
if((right <= heapSize) && (array[right] > array[largest]))
largest = right;
//at this time,array[largest] has been the max(array[left],array[right],array[index])
if(largest != parent)
{
swap(&array[parent], &array[largest]);
maxHeapify(array, largest);
}
}
//the arg len is the max valid index of array, not the real length of array.
//the process to build a maxheap is to modify the heap until the index 0 is a maxheap from index ((index_len - 1) >> 1)
void buildMaxHeap(int *array, int index_len)
{
int i;
heapSize = index_len;
for(i = ((index_len - 1) >> 1);i >= 0;i--)
maxHeapify(array, i);
}
//the arg len is the real length of array
void heap_sort(int array[], int len)
{
int i;
//initialize the max heap
buildMaxHeap(array, len - 1);
for(i = (len - 1);i >= 1;i--)
{
//exchange the array[0] which is the max value to the end sequence zone.
swap(&array[0], &array[i]);
//change the size of unsequence zone.
heapSize--;
//rebuild the maxheap and at this time the children of array[0] are all maxheap, so modify the heap on index 0 only is OK.
maxHeapify(array, 0);
}
}
void print_array(int *a, int len)
{
int i;
for(i = 0;i < len;i++)
{
printf("%d ", a[i]);
}
printf("/n");
}
int main()
{
int a[] = {7,9,0,3,5,1,2,6,8,4};
print_array(a, 10);
heap_sort(a, 10);
print_array(a, 10);
return 0;
}