void MinHeapify(MinHeap* heap, int root) {
if (root > heap->size - 1) { return; }
if (heap->values[root] > heap->values[LeftChild(root)]) {
int tmp = heap->values[root];
heap->values[root] = heap->values[LeftChild(root)];
heap->values[LeftChild(root)] = tmp;
MinHeapify(heap, LeftChild(root));
}
if (heap->values[root] > heap->values[RightChild(root)]) {
int tmp = heap->values[root];
heap->values[root] = heap->values[RightChild(root)];
heap->values[RightChild(root)] = tmp;
MinHeapify(heap, RightChild(root));
}
}
void BuildMinHeap(int* pBuffer, uint32_t nSize)
{
for (int i = nSize/2; i >= 0; --i)
{
MinHeapify(pBuffer, i, nSize);
}
}
int Merge (int arrays[][4], int k, int n, int result[])
{
int i=0, j=0, r=0;
HeapNode *node = NULL, *minnode = NULL;
Heap *h = NULL;
init_heap (&h, k);
for (i=0; i<k; i++) {
node = newnode();
node->data = arrays[i][0];
node->array = i;
node->index = 1;
HeapAdd (h, node, i);
}
MinHeap (h);
r = 0;
for (i=0; i<n*k; i++) {
minnode = getMin (h);
result[r++] = minnode->data;
if (minnode->index < n) {
minnode->data = arrays[minnode->array][minnode->index];
minnode->index++;
} else {
minnode->data = MAX;
}
MinHeapify (h, 0);
}
return 0;
}
int RemoveMin(MinHeap* heap) {
int min = heap->values[0];
heap->values[0] = heap->values[heap->size - 1];
heap->size--;
MinHeapify(heap, 0);
return min;
}
void MinHeapify(int *H,int n,int k) // min-heapify function for setting the ordering property of min heap
{
int min=k;
if((-n+2*k-1)>=0){if(H[-n+2*k-1]<H[min])min=(-n+2*k-1);}
if((-n+2*k)>=0){if(H[-n+2*k]<H[min])min=(-n+2*k);}
if(min==k)return;
else {swap(H[k],H[min]);MinHeapify(H,n,min);}
}
void ReverseHeapSort(int* pBuffer, unsigned int nLen)
{
BuildMinHeap(pBuffer, nLen);
for (int i = nLen - 1; i > 0; --i)
{
std::swap(pBuffer[i], pBuffer[0]);
MinHeapify(pBuffer, 0, i);
}
}
void
MinHeap (Heap *h)
{
if (!h) return;
int i = (h->size/2) + 1;
for (; i>=0; i--) {
MinHeapify (h, i);
}
return;
}
// FOLLOWING ARE IMPLEMENTATIONS OF STANDARD MIN HEAP METHODS
// FROM CORMEN BOOK
// Constructor: Builds a heap from a given array a[] of given size
MinHeap::MinHeap(MinHeapNode a[], int size)
{
heap_size = size;
harr = a; // store address of array
int i = (heap_size - 1)/2;
while (i >= 0)
{
MinHeapify(i);
i--;
}
}
void insert(heap *h, int val)
{
assert(h);
h->data[h->size++] = val;
//#define MINHEAP
#ifdef MINHEAP /*min-heap proprity queue*/
MinHeapify(h);
#else
MaxHeapify(h);
#endif
}
long int extractMinHeap(MinHeap *A)
{
/* We assume that we never call the function when the heap is empty */
long int min = A->arr[1];
A->arr[1] = A->arr[A->heapSize];
(A->heapSize)--;
MinHeapify(A, 1);
return min;
}
void
MinHeap (Heap* h) {
int i =0 ;
i = (h->size - 1)/2;
while (i>=0) {
MinHeapify (h, i);
i--;
}
return;
}
// A recursive method to heapify a subtree with root at given index
// This method assumes that the subtrees are already heapified
void MinHeap::MinHeapify(int i)
{
int l = left(i);
int r = right(i);
int smallest = i;
if (l < heap_size && harr[l].element < harr[i].element)
smallest = l;
if (r < heap_size && harr[r].element < harr[smallest].element)
smallest = r;
if (smallest != i)
{
swap(&harr[i], &harr[smallest]);
MinHeapify(smallest);
}
}
void PartialMinHeapSort(int* pBuffer, uint32_t nLen, uint32_t nPartialSize)
{
BuildMinHeap(pBuffer, nLen);
for (int i = nLen - 1; i > nLen - nPartialSize - 1; --i)
{
std::swap(pBuffer[i], pBuffer[0]);
MinHeapify(pBuffer, 0, i);
}
for (int i = 0; i < nPartialSize + 1; ++i)
{
std::swap(pBuffer[i], pBuffer[nLen - 1 - i]);
}
}
void
MinHeapify (Heap *h, int i) {
int left=2*i+1, right=2*i+2, min=0;
HeapNode *tmp;
min = i;
if (left < h->size && h->harr[left]->data < h->harr[i]->data) {
min = left;
}
if (right < h->size && h->harr[right]->data < h->harr[min]->data) {
min = right;
}
if (min != i) {
tmp = h->harr[i];
h->harr[i] = h->harr[min];
h->harr[min] = tmp;
MinHeapify (h, min);
}
return;
}
void
MinHeapify (Heap *h, int index) {
int l, r, tmp, min;
if (!h || index >= h->size) return;
l = 2*index + 1;
r = 2*index + 2;
min = index;
if (l < h->size && h->harr[l] < h->harr[index]) {
min = l;
}
if (r < h->size && h->harr[r] < h->harr[min]) {
min = r;
}
if (min != index) {
tmp = h->harr[min];
h->harr[min] = h->harr[index];
h->harr[index] = tmp;
MinHeapify (h, min);
}
return;
}
void
klargest (int arr[], int n, int k)
{
if (n <= 0 || k <= 0 || n < k ) return;
int i = 0, min = 0;
Heap *h = NULL;
init_heap (&h, k);
for (i=0; i<k; i++) {
AddHeap (h, arr[i], i);
}
MinHeap (h);
for (; i<n; i++) {
Heapmin (h, &min);
if (arr[i] > min) {
ReplaceMin (h, arr[i]);
MinHeapify (h, 0);
}
}
printHeap (h);
return;
}
void deleteMin(int *H,int& n) // deletes the minimum element in the min heap
{
H[n-1]=H[0];n--;H=H+1;
MinHeapify(H,n,n-1);
}