mirror of
https://github.com/emirpasic/gods
synced 2024-11-06 15:20:25 +00:00
107 lines
2.8 KiB
Go
107 lines
2.8 KiB
Go
/*
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Copyright (c) Emir Pasic, All rights reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 3.0 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library. See the file LICENSE included
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with this distribution for more information.
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*/
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// Implementation of stack using linked list.
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// Used by red-black tree during in-order traversal.
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// Structure is not thread safe.
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// References: http://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29
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package linkedliststack
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import (
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"fmt"
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"github.com/emirpasic/gods/stacks"
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"strings"
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)
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func assertInterfaceImplementation() {
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var _ stacks.Interface = (*Stack)(nil)
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}
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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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type element struct {
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value interface{}
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next *element
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}
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// Instantiates a new empty stack
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func New() *Stack {
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return &Stack{}
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}
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// Pushes a value onto the top of the stack
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func (stack *Stack) Push(value interface{}) {
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stack.top = &element{value, stack.top}
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stack.size += 1
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}
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// Pops (removes) top element on stack and returns it, or nil if stack is empty.
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// Second return parameter is true, unless the stack was empty and there was nothing to pop.
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func (stack *Stack) Pop() (value interface{}, ok bool) {
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if stack.size > 0 {
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value, stack.top = stack.top.value, stack.top.next
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stack.size -= 1
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return value, true
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}
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return nil, false
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}
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// Returns top element on the stack without removing it, or nil if stack is empty.
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// Second return parameter is true, unless the stack was empty and there was nothing to peek.
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func (stack *Stack) Peek() (value interface{}, ok bool) {
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if stack.size > 0 {
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return stack.top.value, true
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}
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return nil, false
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}
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// Returns true if stack does not contain any elements.
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func (stack *Stack) Empty() bool {
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return stack.size == 0
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}
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// Returns number of elements within the stack.
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func (stack *Stack) Size() int {
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return stack.size
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}
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// Removes all elements from the stack.
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func (stack *Stack) Clear() {
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stack.top = nil
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stack.size = 0
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}
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func (stack *Stack) String() string {
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str := "LinkedListStack\n"
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element := stack.top
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elementsValues := []string{}
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for element != nil {
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elementsValues = append(elementsValues, fmt.Sprintf("%v", element.value))
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element = element.next
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}
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for i, j := 0, len(elementsValues)-1; i < j; i, j = i+1, j-1 {
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elementsValues[i], elementsValues[j] = elementsValues[j], elementsValues[i]
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}
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str += strings.Join(elementsValues, ", ")
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return str
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}
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