go: add «232. Implement Queue using Stacks»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/implement-queue-using-stacks.go

@@ -0,0 +1,56 @@
+package implement_queue_using_stacks
+
+import (
+	"slices"
+)
+
+type MyQueue struct {
+	asQueue []int
+	asStack []int
+}
+
+func Constructor() MyQueue {
+	return MyQueue{
+		asQueue: make([]int, 0, 16),
+		asStack: make([]int, 0, 16),
+	}
+}
+
+func (this *MyQueue) Push(x int) {
+	this.asStack = append(this.asStack, x)
+}
+
+func (this *MyQueue) ReverseIfNeeded() {
+	if len(this.asQueue) > 0 {
+		return
+	}
+
+	slices.Reverse(this.asStack)
+	this.asQueue = this.asStack
+	this.asStack = make([]int, 0, 16)
+}
+
+func (this *MyQueue) Pop() int {
+	result := this.Peek()
+	this.asQueue = this.asQueue[:len(this.asQueue)-1]
+	return result
+}
+
+func (this *MyQueue) Peek() int {
+	this.ReverseIfNeeded()
+
+	return this.asQueue[len(this.asQueue)-1]
+}
+
+func (this *MyQueue) Empty() bool {
+	return len(this.asStack) == 0 && len(this.asQueue) == 0
+}
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * obj := Constructor();
+ * obj.Push(x);
+ * param_2 := obj.Pop();
+ * param_3 := obj.Peek();
+ * param_4 := obj.Empty();
+ */

go/implement-queue-using-stacks_test.go

@@ -0,0 +1,49 @@
+package implement_queue_using_stacks
+
+import (
+	"testing"
+)
+
+func TestEmpty(t *testing.T) {
+	obj := Constructor()
+
+	if !obj.Empty() {
+		t.Error("Queue should be empty")
+	}
+}
+
+func TestBasic(t *testing.T) {
+	q := Constructor()
+
+	q.Push(1)
+	q.Push(2)
+
+	if q.Peek() != 1 {
+		t.Error("1 should be at the front of the queue")
+	}
+	if q.Pop() != 1 {
+		t.Error("1 should've been removed from the queue")
+	}
+
+	if q.Empty() {
+		t.Error("Queue shouldn't be empty")
+	}
+
+	q.Push(3)
+
+	if q.Pop() != 2 {
+		t.Error("Queue should've removed 2")
+	}
+
+	if q.Empty() {
+		t.Error("Queue shouldn't be empty")
+	}
+
+	if q.Pop() != 3 {
+		t.Error("Queue should've removed 3")
+	}
+
+	if !q.Empty() {
+		t.Error("Queue should be empty")
+	}
+}