优先队列(堆实现)

#include <iostream>
#include <cstdio>
using namespace std;
int sizeOfheap, mark;

void heapAdjust(int a[], int i, int sizeOfheap)//调整堆 (调整范围:i与i下面的子树)
{
    int lchild = 2 * i;       //i的左孩子节点序号
    int rchild = 2 * i + 1;   //i的右孩子节点序号
    int maxs = i;             //先默认第i个是最大的
    if(i <= sizeOfheap / 2)   //不调整叶子节点
    {
        if(lchild <= sizeOfheap && a[lchild] > a[maxs])
            maxs = lchild;
        if(rchild <= sizeOfheap && a[rchild] > a[maxs])
            maxs = rchild;
        mark = i;
        if(maxs != i)
        {
            swap(a[i], a[maxs]);  //注意下标没换
            mark = i;
            heapAdjust(a, maxs, sizeOfheap); //避免调整之后以max为父节点的子树不是堆
        }
    }
}

void BuildHeap(int a[], int n)
{
    int i;                       //非叶节点最大序号值为size/2
    for(i = n / 2; i >= 1; i--)  //从下面往上面调整
        heapAdjust(a, i, n);
}

void HeapSort(int a[], int n)
{
    int i;
    BuildHeap(a, n);
    for(i = n; i >= 1; i--)
    {
        swap(a[1], a[i]);         //最后面的数和第一个数交换，结果最后一个数变为最大的树了
        heapAdjust(a, 1, i - 1);
    }
}

int top(int a[])
{
    return a[1];
}

int pop(int a[])
{
    if(sizeOfheap < 1)
        printf("heap underflow ! \n");
    int maxs = a[1];                     //优先级最高 ,排在第一个的，这里是最大的
    a[1] = a[sizeOfheap--];              //逻辑上删除了最后一个元素
    heapAdjust(a,1,sizeOfheap);
    return maxs;
}

void changeKey(int a[], int i, int key)//改变第i个元素的关键值key
{
    if(key < a[i])
        printf("new key is smaller than current key!\n");
    a[i] = key;
    heapAdjust(a, 1, sizeOfheap);
}

void push(int a[], int key)  //入队
{
    a[++sizeOfheap] = key;
    heapAdjust(a, 1, sizeOfheap);//调整
}

int main()
{
    int a[100];
    while(scanf("%d", &sizeOfheap) == 1 && sizeOfheap > 0)
    {
        int i;
        for(i = 1; i <= sizeOfheap; i++)  //从下标1开始到n
            scanf("%d", &a[i]);
        printf("%d\n", pop(a));           //输出优先级最高的
        HeapSort(a, sizeOfheap);          //从小到大排序
        for(i = 1; i <= sizeOfheap; i++)
            printf("%d ",a[i]);
        printf("\n\n");
        printf("top: %d\n",top(a));
        printf("\n");
        changeKey(a, 1, 6);
        push(a, 5);
        HeapSort(a, sizeOfheap);
        for(i = 1; i <= sizeOfheap; i++)
            printf("%d ",a[i]);
    }
    return 0;
}