DSOJ Heapsort implementation（堆排序）

题目链接

#include<stdio.h>		//HeapSort implementation
#include<string.h>
#include<stdlib.h>
#define MAXLEN 100001

int len;				//堆中的实际元素的个数

void SiftDown(int *a, int index, int n)
{
	int i, j;
	i = index;
	j = 2 * i;
	a[0] = a[i];		//监视哨
	while (j <= n)
	{
		if (j + 1 <= n&&a[j + 1] < a[j])
			j = j + 1;
		if (a[0] > a[j])
		{
			a[i] = a[j];
			i = j;
			j = 2 * i;
		}
		else
			break;
	}
	a[i] = a[0];
}

void SiftUp(int *a, int index, int n)
{
	int i, j;
	i = index;
	j = i / 2;
	a[0] = a[i];
	while (j > 0)
	{
		if (a[j] > a[0])
		{
			a[i] = a[j];
			i = j;
			j = i / 2;
		}
		else
			break;
	}
	a[i] = a[0];
}

void Insert(int *a, int key)
{
	a[++len] = key;
	SiftUp(a, len, len);
}

void DeleteMin(int *a)
{
	printf("%d\n", a[1]);
	a[1] = a[len--];
	SiftDown(a, 1, len);
}

int main()
{
	int testnum, op, opnum, key;
	int a[MAXLEN];
	scanf("%d", &testnum);
	while (testnum--)
	{
		len = 0;
		scanf("%d", &opnum);
		while (opnum--)
		{
			scanf("%d", &op);
			switch (op)
			{
			case 1:
				scanf("%d", &key);
				Insert(a, key);
				break;
			case 2:
				DeleteMin(a);
				break;
			}
		}
	}
	return 0;
}