44 lines
909 B
Go
44 lines
909 B
Go
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package main
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// Stack is a simple implementation of a LIFO stack
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type Stack struct {
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top *Element
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size int
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}
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// An Element which is stored in the Stack
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type Element struct {
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value interface{} // All types satisfy the empty interface, so we can store anything here.
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next *Element
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}
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// Len returns the stack's length
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func (s *Stack) Len() int {
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return s.size
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}
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// Push a new element onto the stack
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func (s *Stack) Push(value interface{}) {
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s.top = &Element{value, s.top}
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s.size++
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}
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// Pop removes the top element from the stack and returns its value
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// If the stack is empty, return nil
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func (s *Stack) Pop() (value interface{}) {
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if s.size > 0 {
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value, s.top = s.top.value, s.top.next
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s.size--
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return
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}
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return nil
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}
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// Peek lets you see and edit the top value of the stack without popping it
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func (s *Stack) Peek() *interface{} {
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if s.size > 0 {
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return &s.top.value
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}
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return nil
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}
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