/// <summary>
/// fixHeap - this method fixed the heap so it retains the max heap structure
/// </summary>
///
public void fixHeap(int i)
{
int smallest = i; //current smallest int found
int l = 2 * i; //get index of the left child
int r = 2 * i + 1; //get index of the right child
if (l <= size && (h[l].currentNum < h[smallest].currentNum)) //checks to see if the left child is larger than the parent
{
smallest = l;
}
if (r <= size && (h[r].currentNum < h[smallest].currentNum)) //checks to see if the right child is larger than the parent
{
smallest = r;
}
if (smallest != i) //if a new largest is found we need to swap them
{
MergeFile swap = h[i]; //string to hold for swapping two strings
h[i] = h[smallest];
h[smallest] = swap;
fixHeap(smallest); // call the method again
}
}
/// <summary>
/// Insert - inserts an item into the heap and keeps the max heap format
/// </summary>
///
public void Insert(MergeFile item)
{
h[size + 1] = item;
size++; //insert the item and increase the size by 1
int fixsize = size;
do
{
if (size == 1)
{
break; //if the size is 1, then we dont have to execute this loop
}
int currentNode = fixsize; //index of the current node we are at
int parentNode = fixsize / 2; //index of the current node's parent node
fixsize /= 2;
MergeFile temp; //temp variable for holding a node to swap with another
if (h[parentNode].currentNum > h[currentNode].currentNum) //place the new string in the correct spot
{
temp = h[parentNode];
h[parentNode] = h[currentNode];
h[currentNode] = temp;//swap
}
else
{
break;
}
} while (fixsize != 1);
}
/// <summary>
/// extract - this method takes the root node and swaps it with the last node, decreasing the size
/// </summary>
///
public MergeFile Extract()
{
if (size == 0)
{
throw new Exception("The heap is empty."); // if the heap is empty throw an exception
}
MergeFile output; //variable to hold the output node to send back to the handler
MergeFile lastItem; //variable to hold the last item in the array
MergeFile root = h[1]; //the main root node string
output = root; //make the output node the root node to send back to the hander.
lastItem = h[size]; //string of the last item in the heap
h[1] = lastItem;
h[size] = root; //remove the first item and place in the last spot
size--;
fixHeap(1); //we need to fix the heap starting with the root node
return(output); //return the extracted node
}