Thread: heap question

i tried really hard to avoid posting this question but i cant seem to spot the problem

so here it is..
basically i want to print the highest number of 'search_counts' from a heap.
> there is an array of struct HEAP
> there is only 1 element in HEAP , it is DATA *dataPtr , basically it points to a struct DATA (which has been allocated memory dynamically)
> i have to delete the top most item from the heap ary and print it and then reheapDown to get it back to a heap form.

problem: it prints all but the last element correctly. for the last element it prints out garbage.

i have been through the debugger so many times but yet it failed.

here is the code

int j is the count of how many elements were inserted into the heap ary
int whatFn is basically a checker to see that if the number of elements inserted was less than the HEAP_SIZE which is 7 then use j otherwise use HEAP_SIZE for the restrictor

Code:

void printHeap1 (HEAP *ary, int j, int whatFn)
{
	int i = 0;
	HEAP *pWalker, *pCur, *pLast, dataOut;

	pCur = ary;

	printf("--- 7 Most popular searches ---\n");

	if (whatFn == NOT_EQUAL)
	{
		pLast = &ary[j];
		j--;
		for (pWalker = pCur; pWalker < pLast; pWalker++)
		{
			if (deleteHeap (ary, &j, &dataOut) == 1)
				printToScreen (&dataOut, "heap");
			else
				printf("Unable to delete node\n");
		}
	}
	else
	{
		pLast = &ary[HEAP_SIZE -1];
		j--;
		for (pWalker = pCur; pWalker < pLast; pWalker++)
		{
			if (deleteHeap (ary, &j, &dataOut) == 1)
				printToScreen (&dataOut, "heap");
			else
				printf("Unable to delete node\n");
		}
	}
	return;
}

this goes to the delete heap function that is

Code:

int deleteHeap (HEAP *heap, int *last, HEAP *dataOut)
{
//	int item;

	if (*last < 0)
	{
		return 0;
	}

	dataOut->dataPtr = heap[0].dataPtr;
	heap [0].dataPtr = heap [*last].dataPtr;
//	heap[*last].dataPtr = NULL;
	(*last)--;

	reheapDown (heap, 0, *last);

	return 1;
}

this later goes to the reheapDown function which is

Code:

void reheapDown (HEAP *heap, int root, int last)
{
	DATA hold, leftKey, rightKey, largeChildKey;
	int largeChildIndex = 0;
	//int parent;

	if ((root * 2 + 1) <= last)
	{
		leftKey = *(heap [root * 2 + 1].dataPtr);

		if ((root * 2 + 2) <= last)
		{
			rightKey = *(heap [root * 2 + 2].dataPtr);
		}
		else
		{
			rightKey.search_count = -1;
		}

		if (leftKey.search_count > rightKey.search_count)
		{
			largeChildKey = leftKey;
			largeChildIndex = root * 2 + 1;
		}
		else
		{
			largeChildKey = rightKey;
			largeChildIndex = root * 2 + 2;
		}

		if (heap[root].dataPtr->search_count < heap [largeChildIndex].dataPtr->search_count)
		{
			hold = *(heap [root].dataPtr);
			heap [root].dataPtr = heap [largeChildIndex].dataPtr;
			heap [largeChildIndex].dataPtr = &hold;

			reheapDown (heap, largeChildIndex, last);
		}
	}
	return;
}

any form of help is appreciated. i just need someone to spot the error. i can fix the rest myself
thanks

dont worry about it

i fixed it