51 lines
729 B
Go
51 lines
729 B
Go
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package stack
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// "Generic" item.
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// When type parameters will land this type became
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// type Item[T any] T
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type Item interface{}
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type Stack interface {
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Push(Item)
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Pop() Item
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Size() int
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IsEmpty() bool
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}
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// We use linked list as internal data structure
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// to get O(1) speed for push and pop opeartions
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type node struct {
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item Item
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next *node
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}
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type stack struct {
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size int
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head *node
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}
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func NewStack() Stack {
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return &stack{}
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}
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func (s *stack) Push(item Item) {
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next := s.head
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s.head = &node{item, next}
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s.size++
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}
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func (s *stack) Pop() Item {
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head := s.head
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s.head = head.next
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s.size--
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return head.item
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}
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func (s *stack) Size() int {
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return s.size
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}
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func (s *stack) IsEmpty() bool {
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return s.size == 0
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}
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