test: add unit test for PriorityQueue Enqueue function

datastructure/queue/priorityqueue.go

@@ -1,6 +1,10 @@
 package datastructure
 
-import "github.com/duke-git/lancet/v2/lancetconstraints"
+import (
+	"errors"
+
+	"github.com/duke-git/lancet/v2/lancetconstraints"
+)
 
 // PriorityQueue is a priority queue implemented by binary heap tree
 // type T should implements Compare function in lancetconstraints.Comparator interface.
@@ -12,8 +16,8 @@ type PriorityQueue[T any] struct {
 
 // NewPriorityQueue return a pointer of PriorityQueue
 // param `comparator` is used to compare valuse in the heap
-func NewPriorityQueue[T any](capacity int, comparator lancetconstraints.Comparator) *NewPriorityQueue[T] {
-	return &NewPriorityQueue[T]{
+func NewPriorityQueue[T any](capacity int, comparator lancetconstraints.Comparator) *PriorityQueue[T] {
+	return &PriorityQueue[T]{
 		items:      make([]T, capacity+1),
 		size:       0,
 		comparator: comparator,
@@ -27,5 +31,29 @@ func (q *PriorityQueue[T]) IsEmpty() bool {
 
 // IsFull checks if the queue capacity is full or not
 func (q *PriorityQueue[T]) IsFull() bool {
-	return q.size == len(q.items)
+	return q.size == len(q.items)-1
+}
+
+// Enqueue insert value into queue
+func (q *PriorityQueue[T]) Enqueue(val T) error {
+	if q.IsFull() {
+		return errors.New("queue is already full.")
+	}
+	q.size++
+	q.items[q.size] = val
+	q.swim(q.size)
+	return nil
+}
+
+// swim when child's key is larger than parent's key, exchange them.
+func (q *PriorityQueue[T]) swim(index int) {
+	for index > 1 && q.comparator.Compare(index/2, index) < 0 {
+		q.swap(index, index/2)
+		index = index / 2
+	}
+}
+
+// swap the two values at index i and j
+func (q *PriorityQueue[T]) swap(i, j int) {
+	q.items[i], q.items[j] = q.items[j], q.items[i]
 }