feat: add MaxHeap

datastructure/heap/maxheap.go

@@ -23,7 +23,13 @@ func NewMaxHeap[T any](comparator lancetconstraints.Comparator) *MaxHeap[T] {
 	}
 }
 
-// heapifyUp heapify the data from bottom to up
+// Push value into the heap
+func (h *MaxHeap[T]) Push(value T) {
+	h.data = append(h.data, value)
+	h.heapifyUp(len(h.data) - 1)
+}
+
+// heapifyUp heapify the data from bottom to top
 func (h *MaxHeap[T]) heapifyUp(i int) {
 	for h.comparator.Compare(h.data[parentIndex(i)], h.data[i]) < 0 {
 		h.swap(parentIndex(i), i)
@@ -31,6 +37,70 @@ func (h *MaxHeap[T]) heapifyUp(i int) {
 	}
 }
 
+// Pop return the largest value, and remove it from the heap
+// if heap is empty, return zero value and fasle
+func (h *MaxHeap[T]) Pop(value T) (T, bool) {
+	var val T
+	if h.Size() == 0 {
+		return val, false
+	}
+
+	val = h.data[0]
+	l := len(h.data) - 1
+
+	h.data[0] = h.data[l]
+	h.data = h.data[:l]
+	h.heapifyDown(0)
+
+	return val, true
+}
+
+// heapifyDown heapify the data from top to bottom
+func (h *MaxHeap[T]) heapifyDown(i int) {
+	lastIndex := len(h.data) - 1
+	l, r := leftChildIndex(i), rightChildIndex(i)
+	childToCompare := 0
+
+	for l <= lastIndex {
+		if l == lastIndex {
+			childToCompare = l
+		} else if h.comparator.Compare(h.data[l], h.data[r]) > 0 {
+			childToCompare = l
+		} else {
+			childToCompare = r
+		}
+
+		if h.comparator.Compare(h.data[i], h.data[childToCompare]) < 0 {
+			h.swap(i, childToCompare)
+			i = childToCompare
+			l, r = leftChildIndex(i), rightChildIndex(i)
+		} else {
+			break
+		}
+	}
+}
+
+// Peek returns the largest element from the heap without removing it.
+// if heap is empty, it returns zero value and false.
+func (h *MaxHeap[T]) Peek() (T, bool) {
+	if h.Size() == 0 {
+		var val T
+		return val, false
+	}
+
+	return h.data[0], true
+}
+
+// Size return the number of elements in the heap
+func (h *MaxHeap[T]) Size() int {
+	return len(h.data)
+}
+
+// Data return data of the heap
+func (h *MaxHeap[T]) Data() []T {
+	return h.data
+}
+
 // parentIndex get parent index of the given index
 func parentIndex(i int) int {
 	return (i - 1) / 2