堆的代碼實現

//假設小堆
typedef int HDataType;
typedef struct heap
{
    HDataType* _data;
    int _size;
    int _capacity;
}heap;
void Swap(int* a, int* b)
{
    int tmp = a;
    a = b;
    b = tmp;
}
void heapInit(heap* hp)
{
    if (hp == NULL)
        return;
    //空堆
    hp->_data = NULL;
    hp->_size = hp->_capacity = 0; 
}
void heapPush(heap* hp, HDataType val)
{
    checkCapacity(hp);
    //尾插
    hp->_data[hp->_size++] = val;
    //向上調整
    shiftUp(hp->_data, hp->_size, hp->_size - 1);
}
void hpeaPop(heap* hp)
{
    if (hp->_size > 0)
    {
        //交換
        Swap(&hp->_data[0], &hp->_data[hp->_size - 1]);
        hp->_size--;
        //從堆頂位置向下調整
        shiftDown(hp->_data, hp->_size, 0);
    }
}
HDataType heapTop(heap* hp)
{
    return hp->_data[0];
}
int heapEmpty(heap* hp)
{
    if (hp == NULL || hp->_size == 0)
        return 1;
    else 
        return 0;
}
void checkCapacity(heap* hp)
{
    if (hp->_size = hp->_capacity)
    {
        int newC = hp->_capacity == 0 ? 1 : 2 * hp->_capacity;
        hp->_data = (HDataType*)relloc(hp->_data, sizeof(HDataType)*newC);
        hp->_capacity = newC;
    }
}

/*
//向下調整
#include<stdio.h>
void shiftDown(int* arr, int n, int cur)
{
    //找到孩子的位置
    //左孩子
    int child = 2 * cur + 1;
    while (child < n)
    {
        //從左孩子找最小的
        if (child + 1 < n&&arr[child] > arr[child + 1])
            ++child;
        //和當前數據作比較
        //1.孩子小於當前  調整
        if (arr[child] < arr[cur])
        {
            int tmp = arr[child];
            arr[child] = arr[cur];
            arr[cur] = tmp;
            //更新位置，繼續調整
            cur = child;
            child = 2 * cur + 1;
        }
        else
            //2.孩子>=當前   不調整
            break;
    }

}
void test()
{
    int arr[] = { 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 };
    int n = sizeof(arr) / sizeof(arr[0]);
    //建堆：從最後一個非葉子節點開始，向下調整
    for (int i = (n - 2) / 2; i >= 0; i--)
    {
        shiftDown(arr, n, i);
    }
}
//void test()
//{
//  int arr[] = { 10, 5, 3, 8, 7, 6 };
//  shiftDown(arr, sizeof(arr) / sizeof(arr[0]), 0);
//}
int main()
{
    test();
    return 0;
}*/