THINK-PRO BLOG

#include <stdio.h>
#include <stdlib.h>

#define minus_inf -32767

int PARENT(int index){ return index/2; }
int LCHILD(int index){ return index*2; }
int RCHILD(int index){ return index*2+1; }

void array_swap(int arr[], int a, int b)
{
	int temp;
	temp = arr[a];
	arr[a] = arr[b];
	arr[b] = temp;
}

void Heapify(int arr[], int current, int length)
{
	int left, right, largest;
	left=LCHILD(current);
	right=RCHILD(current);

	if((right<=length) && (arr[right]>arr[current]))
		largest = right;
	else
		largest = current;

	if((left<=length) && (arr[left]>arr[largest]))
		largest = left;

	if(largest != current)
	{
		array_swap(arr, current, largest);
		Heapify(arr, largest, length);
	}
}

void PRINT(int arr[], int length)
{
	int i=0;
	for(i=1; i<=length; i++)
		printf("%d ", arr[i]);
}

int EXTRACT_MAX(int arr[], int length)
{
	if(length < 1)		// "heap underflow"
		return minus_inf;
	int max = arr[1];
	arr[1] = arr[length];
	length --;
	Heapify(arr, 1, length);
	return max;
}

void INCREASE_KEY(int arr[], int index, int key)
{
	int tmp=0;
	if(key < arr[index])		// not increasing, then fail.
		return;

	arr[index] = key;
	while(index>1 && arr[PARENT(index)]<arr[index])
	{
		/* EXCHANGE CURRENT WITH PARENT */
		tmp = arr[index];
		arr[index] = arr[index/2];
		arr[index/2] = tmp;

		index = PARENT(index);
	}
}

void INSERT(int arr[], int length, int key)
{
	arr[length] = minus_inf;
	INCREASE_KEY(arr, length, key);
}

int main(void)
{
	int arr[100000];
	int ext[100000];
	int length=0, extlength=0;

	int op, tmp, i;
	int index, num;

	int quit=0;

	//INSERT(arr, length, 1); length++;
	//INSERT(arr, length, 2); length++;

	while(quit==0)
	{
		scanf("%d", &op);
		switch(op)
		{
		case 0:// print
			quit=1;		// terminate this program.
			break;

		case 1:// insert
			scanf("%d", &num);
			length++;
			arr[length] = num;
			INCREASE_KEY(arr, length, num);
			break;

		case 2:// extract
			extlength++;
			ext[extlength] = arr[1];

			tmp = arr[1];
			arr[1] = arr[length];
			arr[length] = tmp;

			length--;
			Heapify(arr, 1, length);
			break;

		case 3:// replace
			scanf("%d %d", &index, &num);
			arr[index] = num;
			if(index != 1 && arr[index] > arr[PARENT(index)])
				INCREASE_KEY(arr, index, num);
			else
				Heapify(arr, index, length);
			break;
	
		default:
			break;
		}
	}

	for(i=1; i<=extlength; i++)
		printf("%d ", ext[i]);

	printf("\n");
	for(i=1; i<=length; i++)
		printf("%d ", arr[i]);

	return 0;
}