堆排序

#include<iostream>

using namespace std;

//节点从0开始所以会多1
int left(int i)
{
return i * 2 + 1;
}

int right(int i)
{
return i * 2 + 2;
}

//使得节点i及其子节点都是最大堆
void Max_Heapfiy(int *A, int length, int i)
{
int Right = right(i), Left = left(i), largest = i;
if (Left < length && A[Left] > A[largest])
{
largest = Left;
}
if (Right < length && A[Right] > A[largest])
{
largest = Right;
}
if (largest != i)
{
int temp = A[i];
A[i] = A[largest];
A[largest] = temp;
Max_Heapfiy(A, length, largest);
}
}

void Build_Max_Heap(int *A, int length)
{
//从最后一个非叶子节点开始，到根节点，因为Max_Heapfiy调用时必须保证子节点是最大堆
for (int i = (length - 1) / 2; i >= 0; i--)
{
Max_Heapfiy(A, 5, i);
}
}

void px(int *A, int length)
{
Build_Max_Heap(A, length);
for (int i = length - 1; i >= 1; i--)
{
int temp = A[i];
A[i] = A[0];
A[0] = temp;
Max_Heapfiy(A, i, 0);
}
}

int main()
{
int a[5] = {5,3,2,1,4};
px(a, 5);
system("pause");
return 0;
}