elementary priority queue

1 files changed, 53 insertions, 0 deletions

diff --git a/queue/elementarypq.go b/queue/elementarypq.go
new file mode 100644
index 0000000..31cab9f
--- /dev/null
+++ b/queue/elementarypq.go
@@ -0,0 +1,53 @@
+package queue
+
+import "algorithms/ds"
+
+type ElementaryPQ struct {
+	a    ds.ArrayList
+	size int
+}
+
+func NewElementaryPQ(capacity int) ElementaryPQ {
+	return ElementaryPQ{make(ds.ArrayList, 0, capacity), 0}
+}
+
+func (q ElementaryPQ) Insert(a int) {
+	q.a = append(q.a, a)
+	q.size++
+}
+
+func (q ElementaryPQ) Max() (max int) {
+	_, max = q.max()
+	return
+}
+
+func (q ElementaryPQ) DeleteMax() int {
+	if q.Empty() {
+		return 0
+	}
+
+	ind, max := q.max()
+	for i := ind + 1; i < q.Size(); i++ {
+		q.a[i-1] = q.a[i]
+	}
+	q.size--
+
+	return max
+}
+
+func (q ElementaryPQ) Empty() bool {
+	return q.Size() == 0
+}
+
+func (q ElementaryPQ) Size() int {
+	return q.size
+}
+
+func (q ElementaryPQ) max() (ind, max int) {
+	for i, a := range q.a {
+		if a > max {
+			ind, max = i, a
+		}
+	}
+	return ind, max
+}