From 2ac9c4d384443bd485148e0d28f476c2ac76b14f Mon Sep 17 00:00:00 2001 From: Emir Pasic Date: Thu, 5 Mar 2015 06:55:53 +0100 Subject: [PATCH] - implemented linke list stack - minor changes on other libs - tests included --- stacks/linkedliststack/linkedliststack.go | 92 +++++++++++++++++++ .../linkedliststack/linkedliststack_test.go | 72 +++++++++++++++ trees/redblacktree/redblacktree.go | 9 +- 3 files changed, 169 insertions(+), 4 deletions(-) create mode 100644 stacks/linkedliststack/linkedliststack.go create mode 100644 stacks/linkedliststack/linkedliststack_test.go diff --git a/stacks/linkedliststack/linkedliststack.go b/stacks/linkedliststack/linkedliststack.go new file mode 100644 index 0000000..00cdc89 --- /dev/null +++ b/stacks/linkedliststack/linkedliststack.go @@ -0,0 +1,92 @@ +/* +Copyright (c) Emir Pasic, All rights reserved. + +This library is free software; you can redistribute it and/or +modify it under the terms of the GNU Lesser General Public +License as published by the Free Software Foundation; either +version 3.0 of the License, or (at your option) any later version. + +This library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Lesser General Public License for more details. + +You should have received a copy of the GNU Lesser General Public +License along with this library. See the file LICENSE included +with this distribution for more information. +*/ + +// Implementation of stack using linked list. +// Used by red-black tree during in-order traversal. +// Structure is not thread safe. +// References: http://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29 + +package linkedliststack + +import ( + "fmt" +) + +type Stack struct { + top *element + size int +} + +type element struct { + value interface{} + next *element +} + +// Instantiates a new empty stack +func New() *Stack { + return &Stack{} +} + +// Pushes a value onto the top of the stack +func (stack *Stack) Push(value interface{}) { + stack.top = &element{value, stack.top} + stack.size += 1 +} + +// Pops (removes) top element on stack and returns it, or nil if stack is empty. +// Second return parameter is true, unless the stack was empty and there was nothing to pop. +func (stack *Stack) Pop() (value interface{}, ok bool) { + if stack.size > 0 { + value, stack.top = stack.top.value, stack.top.next + stack.size -= 1 + return value, true + } + return nil, false +} + +// Returns top element on the stack without removing it, or nil if stack is empty. +// Second return parameter is true, unless the stack was empty and there was nothing to peek. +func (stack *Stack) Peek() (value interface{}, ok bool) { + if stack.size > 0 { + return stack.top.value, true + } + return nil, false +} + +func (stack *Stack) Empty() bool { + return stack.size == 0 +} + +func (stack *Stack) Size() int { + return stack.size +} + +func (stack *Stack) String() string { + str := "RedBlackTree\n" + element := stack.top + elementsValues := []string{} + for element != nil { + elementsValues = append(elementsValues, fmt.Sprintf("%v ", element.value)) + element = element.next + } + for i, j := 0, len(elementsValues)-1; i < j; i, j = i+1, j-1 { + elementsValues[i], elementsValues[j] = elementsValues[j], elementsValues[i] + } + str += fmt.Sprintf("#v", elementsValues) + return str +} diff --git a/stacks/linkedliststack/linkedliststack_test.go b/stacks/linkedliststack/linkedliststack_test.go new file mode 100644 index 0000000..9503736 --- /dev/null +++ b/stacks/linkedliststack/linkedliststack_test.go @@ -0,0 +1,72 @@ +/* +Copyright (c) Emir Pasic, All rights reserved. + +This library is free software; you can redistribute it and/or +modify it under the terms of the GNU Lesser General Public +License as published by the Free Software Foundation; either +version 3.0 of the License, or (at your option) any later version. + +This library is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Lesser General Public License for more details. + +You should have received a copy of the GNU Lesser General Public +License along with this library. See the file LICENSE included +with this distribution for more information. +*/ + +package linkedliststack + +import ( + "testing" +) + +func TestLinkedListStack(t *testing.T) { + + stack := New() + + if actualValue := stack.Empty(); actualValue != true { + t.Errorf("Got %v expected %v", actualValue, true) + } + + // insertions + stack.Push(1) + stack.Push(2) + stack.Push(3) + + if actualValue := stack.Empty(); actualValue != false { + t.Errorf("Got %v expected %v", actualValue, false) + } + + if actualValue := stack.Size(); actualValue != 3 { + t.Errorf("Got %v expected %v", actualValue, 3) + } + + if actualValue, ok := stack.Peek(); actualValue != 3 || !ok { + t.Errorf("Got %v expected %v", actualValue, 3) + } + + stack.Pop() + + if actualValue, ok := stack.Peek(); actualValue != 2 || !ok { + t.Errorf("Got %v expected %v", actualValue, 2) + } + + if actualValue, ok := stack.Pop(); actualValue != 2 || !ok { + t.Errorf("Got %v expected %v", actualValue, 2) + } + + if actualValue, ok := stack.Pop(); actualValue != 1 || !ok { + t.Errorf("Got %v expected %v", actualValue, 1) + } + + if actualValue, ok := stack.Pop(); actualValue != nil || ok { + t.Errorf("Got %v expected %v", actualValue, nil) + } + + if actualValue := stack.Empty(); actualValue != true { + t.Errorf("Got %v expected %v", actualValue, true) + } + +} diff --git a/trees/redblacktree/redblacktree.go b/trees/redblacktree/redblacktree.go index 56a6af9..9e8baff 100644 --- a/trees/redblacktree/redblacktree.go +++ b/trees/redblacktree/redblacktree.go @@ -20,6 +20,7 @@ with this distribution for more information. // Used by TreeSet and TreeMap. // Structure is not thread safe. // References: http://en.wikipedia.org/wiki/Red%E2%80%93black_tree + package redblacktree import ( @@ -103,7 +104,7 @@ func (tree *Tree) Put(key interface{}, value interface{}) { // Searches the node in the tree by key and returns its value or nil if key is not found in tree. // Second return parameter is true if key was found, otherwise false. // Key should adhere to the comparator's type assertion, otherwise method panics. -func (tree *Tree) Get(key interface{}) (interface{}, bool) { +func (tree *Tree) Get(key interface{}) (value interface{}, found bool) { node := tree.lookup(key) if node != nil { return node.value, true @@ -144,8 +145,8 @@ func (tree *Tree) Remove(key interface{}) { } // Returns true if tree does not contain any nodes -func (tree *Tree) IsEmpty() bool { - return tree.root == nil +func (tree *Tree) Empty() bool { + return tree.size == 0 } // Returns number of nodes in the tree. @@ -155,7 +156,7 @@ func (tree *Tree) Size() int { func (tree *Tree) String() string { str := "RedBlackTree\n" - if !tree.IsEmpty() { + if !tree.Empty() { output(tree.root, "", true, &str) } return str