Refactoring : isolate stack manipulation into their own package

pkg/pointer/stack.go

@@ -1,54 +1,13 @@
 package pointer
 
-type Stack struct {
-	size   int
-	height int
-	data   []int
-	next   *Stack // Pointer to the next element in the stack stack
+func (ss *StackStack) Pop() int {
+	return ss.head.Pop()
 }
 
-func NewStack() *Stack {
-	return &Stack{
-		size:   32,
-		height: 0,
-		data:   make([]int, 32),
-		next:   nil,
-	}
+func (ss *StackStack) Push(v int) {
+	ss.head.Push(v)
 }
 
-func (s *Stack) Clear() {
-	s.height = 0
-}
-
-func (s *Stack) Duplicate() {
-	if s.height > 0 {
-		s.Push(s.data[s.height-1])
-	} else {
-		s.Push(0)
-		s.Push(0)
-	}
-}
-
-func (s *Stack) Pop() int {
-	if s.height > 0 {
-		s.height--
-		return s.data[s.height]
-	}
-	return 0
-}
-
-func (s *Stack) Push(value int) {
-	if s.height >= s.size {
-		s.size += 32
-		s.data = append(s.data, make([]int, 32)...)
-	}
-	s.data[s.height] = value
-	s.height++
-}
-
-func (s *Stack) Swap() {
-	a := s.Pop()
-	b := s.Pop()
-	s.Push(a)
-	s.Push(b)
+func (s *StackStack) YCommandPick(n int, h int) {
+	s.head.YCommandPick(n, h)
 }