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Emir Pasic 9 years ago
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README.md
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Implementation of various data structures in Go.
## Implementations
- Sets:
- HashSet (unordered)
- TreeSet (ordered)
- Stacks:
- LinkedListStack
- ArrayStack
- Maps:
- HashMap (unordered)
- TreeMap (ordered)
- Tree:
- RedBlackTree
## Data Structures
- [Sets](#Sets)
- [HashSet](#HashSet)
- [TreeSet](#TreeSet)
- [Stacks](#Stacks)
- [LinkedListStack](#LinkedListStack)
- [ArrayStack](#ArrayStack)
- [Maps](#Maps)
- [HashMap](#HashMap)
- [TreeMap](#TreeMap)
- [Trees](#Trees)
- [RedBlackTree](#RedBlackTree)
###Sets
A set is a data structure that can store elements and no repeated values. It is a computer implementation of the mathematical concept of a finite set. Unlike most other collection types, rather than retrieving a specific element from a set, one typically tests an element for membership in a set. This structed is often used to ensure that no duplicates are present in a collection.
All sets implement the set interface with the following methods:
```go
Add(items ...interface{})
Remove(items ...interface{})
Contains(items ...interface{}) bool
Empty() bool
Size() int
Clear()
Values() []interface{}
```
####HashSet
This structure implements the Set interface and is backed by a hash table (actually a Go's map). It makes no guarantees as to the iteration order of the set, since Go randomizes this iteration order on maps.
This structure offers constant time performance for the basic operations (add, remove, contains and size).
```go
package main
import "github.com/emirpasic/gods/sets/hashset"
func main() {
set := hashset.New() // empty
set.Add(1) // 1
set.Add(2, 2, 3, 4, 5) // 3, 1, 2, 4, 5 (random order, duplicates ignored)
set.Remove(4) // 5, 3, 2, 1 (random order)
set.Remove(2, 3) // 1, 5 (random order)
set.Contains(1) // true
set.Contains(1, 5) // true
set.Contains(1, 6) // false
_ = set.Values() // []int{5,1} (random order)
set.Clear() // empty
set.Empty() // true
set.Size() // 0
}
```
####TreeSet
This structure implements the Set interface and is backed by a red-black tree to keep the elements sorted with respect to the comparator.
This implementation provides guaranteed log(n) time cost for the basic operations (add, remove and contains).
```go
package main
import "github.com/emirpasic/gods/sets/treeset"
func main() {
set := treeset.NewWithIntComparator() // empty (keys are of type int)
set.Add(1) // 1
set.Add(2, 2, 3, 4, 5) // 1, 2, 3, 4, 5 (in order, duplicates ignored)
set.Remove(4) // 1, 2, 3, 5 (in order)
set.Remove(2, 3) // 1, 5 (in order)
set.Contains(1) // true
set.Contains(1, 5) // true
set.Contains(1, 6) // false
_ = set.Values() // []int{1,5} (in order)
set.Clear() // empty
set.Empty() // true
set.Size() // 0
}
```
###Stacks
The stack interface represents a last-in-first-out (LIFO) collection of objects. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack, a method to check whether the stack is empty and the size (number of elements).
All stacks implement the stack interface with the following methods:
```go
Push(value interface{})
Pop() (value interface{}, ok bool)
Peek() (value interface{}, ok bool)
Empty() bool
Size() int
Clear()
```
####LinkedListStack
This stack structure is based on a linked list, i.e. each previous element has a point to the next.
All operations are guaranted constant time performance.
```go
package main
import lls "github.com/emirpasic/gods/stacks/linkedliststack"
func main() {
stack := lls.New() // empty
stack.Push(1) // 1
stack.Push(2) // 1, 2
_, _ = stack.Peek() // 2,true
_, _ = stack.Pop() // 2, true
_, _ = stack.Pop() // 1, true
_, _ = stack.Pop() // nil, false (nothing to pop)
stack.Push(1) // 1
stack.Clear() // empty
stack.Empty() // true
stack.Size() // 0
}
```
####ArrayStack
This stack structure is based on a array.
All operations are guaranted constant time performance.
```go
package main
import "github.com/emirpasic/gods/stacks/arraystack"
func main() {
stack := arraystack.New() // empty
stack.Push(1) // 1
stack.Push(2) // 1, 2
_, _ = stack.Peek() // 2,true
_, _ = stack.Pop() // 2, true
_, _ = stack.Pop() // 1, true
_, _ = stack.Pop() // nil, false (nothing to pop)
stack.Push(1) // 1
stack.Clear() // empty
stack.Empty() // true
stack.Size() // 0
}
```
###Maps
Structure that maps keys to values. A map cannot contain duplicate keys and each key can map to at most one value.
All maps implement the map interface with the following methods:
```go
Put(key interface{}, value interface{})
Get(key interface{}) (value interface{}, found bool)
Remove(key interface{})
Empty() bool
Size() int
Clear()
Keys() []interface{}
Values() []interface{}
```
####HashMap
Map structure based on hash tables, more exactly, Go's map. Keys are unordered.
All operations are guaranted constant time performance, except _Key()_ and _Values()_ retrieval that of linear time performance.
```go
package main
import "github.com/emirpasic/gods/maps/hashmap"
func main() {
m := hashmap.New() // empty
m.Put(1, "x") // 1->x
m.Put(2, "b") // 2->b, 1->x (random order)
m.Put(1, "a") // 2->b, 1->a (random order)
_, _ = m.Get(2) // b, true
_, _ = m.Get(3) // nil, false
_ = m.Values() // []interface {}{"b", "a"} (random order)
_ = m.Keys() // []interface {}{1, 2} (random order)
m.Remove(1) // 2->b
m.Clear() // empty
m.Empty() // true
m.Size() // 0
}
```
####TreeMap
Map structure based on our red-black tree implementation. Keys are ordered with respect to the passed comparator.
_Put()_, _Get()_ and _Remove()_ are guaranteed log(n) time performance.
_Key()_ and _Values()_ methods return keys and values respectively in order of the keys. These meethods are quaranteed linear time performance.
```go
package main
import "github.com/emirpasic/gods/maps/treemap"
func main() {
m := treemap.NewWithIntComparator() // empty (keys are of type int)
m.Put(1, "x") // 1->x
m.Put(2, "b") // 1->x, 2->b (in order)
m.Put(1, "a") // 1->a, 2->b (in order)
_, _ = m.Get(2) // b, true
_, _ = m.Get(3) // nil, false
_ = m.Values() // []interface {}{"a", "b"} (in order)
_ = m.Keys() // []interface {}{1, 2} (in order)
m.Remove(1) // 2->b
m.Clear() // empty
m.Empty() // true
m.Size() // 0
}
```
###Trees
A tree is a widely used data data structure that simulates a hierarchical tree structure, with a root value and subtrees of children, represented as a set of linked nodes; thus no cyclic links.
####RedBlackTree
A red–black tree is a binary search tree with an extra bit of data per node, its color, which can be either red or black. The extra bit of storage ensures an approximately balanced tree by constraining how nodes are colored from any path from the root to the leaf. Thus, it is a data structure which is a type of self-balancing binary search tree.[Wikipedia](http://en.wikipedia.org/wiki/Red%E2%80%93black_tree)
The balancing of the tree is not perfect but it is good enough to allow it to guarantee searching in O(log n) time, where n is the total number of elements in the tree. The insertion and deletion operations, along with the tree rearrangement and recoloring, are also performed in O(log n) time.[Wikipedia](http://en.wikipedia.org/wiki/Red%E2%80%93black_tree)
[![Build Status](http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Red-black_tree_example.svg/500px-Red-black_tree_example.svg.png)](http://en.wikipedia.org/wiki/Red%E2%80%93black_tree)
```go
package main
import (
"fmt"
rbt "github.com/emirpasic/gods/trees/redblacktree"
)
func main() {
tree := rbt.NewWithIntComparator() // empty(keys are of type int)
tree.Put(1, "x") // 1->x
tree.Put(2, "b") // 1->x, 2->b (in order)
tree.Put(1, "a") // 1->a, 2->b (in order, replacement)
tree.Put(3, "c") // 1->a, 2->b, 3->c (in order)
tree.Put(4, "d") // 1->a, 2->b, 3->c, 4->d (in order)
tree.Put(5, "e") // 1->a, 2->b, 3->c, 4->d, 5->e (in order)
tree.Put(6, "f") // 1->a, 2->b, 3->c, 4->d, 5->e, 6->f (in order)
fmt.Println(m)
//
// RedBlackTree
// │ ┌── 6
// │ ┌── 5
// │ ┌── 4
// │ │ └── 3
// └── 2
// └── 1
_ = tree.Values() // []interface {}{"a", "b", "c", "d", "e", "f"} (in order)
_ = tree.Keys() // []interface {}{1, 2, 3, 4, 5, 6} (in order)
tree.Remove(2) // 1->a, 3->c, 4->d, 5->e, 6->f (in order)
fmt.Println(m)
//
// RedBlackTree
// │ ┌── 6
// │ ┌── 5
// └── 4
// │ ┌── 3
// └── 1
tree.Clear() // empty
tree.Empty() // true
tree.Size() // 0
}
```
## Motivations
@ -42,11 +322,11 @@ Collections and data structures found in other languages: Java Collections, C++
**Solid documentation and examples**:
- TODO
- Learning by example.
**Production ready**:
- TODO
- Still waiting for the project to mature and be used in some heavy back-end tasks.
There is often a tug of war between speed and memory when crafting algorithms. We choose to optimize for speed in most cases within reasonable limits on memory consumption.
@ -56,8 +336,14 @@ Thread safety is not a concern of this project, this should be handled at a high
`go test -v -bench . -benchmem -benchtime 1s ./...`
## Contributing
Biggest contribution towards this library is to use it and give us feedback for further improvements and additions.
For direct contributions, branch of from master and do _pull request_.
## License
Copyright (c) Emir Pasic, All rights reserved.
Copyright (c) Emir Pasic , All rights reserved.
GNU Lesser General Public License Version 3, see [LICENSE](https://github.com/emirpasic/gods/blob/master/LICENSE) for more details.

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examples/arraystack.go
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package examples
import "github.com/emirpasic/gods/stacks/arraystack"
func arraystackExample() {
stack := arraystack.New() // empty
stack.Push(1) // 1
stack.Push(2) // 1, 2
_, _ = stack.Peek() // 2,true
_, _ = stack.Pop() // 2, true
_, _ = stack.Pop() // 1, true
_, _ = stack.Pop() // nil, false (nothing to pop)
stack.Push(1) // 1
stack.Clear() // empty
stack.Empty() // true
stack.Size() // 0
}

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examples/hashmap.go
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package examples
import "github.com/emirpasic/gods/maps/hashmap"
func hashmapExample() {
m := hashmap.New() // empty
m.Put(1, "x") // 1->x
m.Put(2, "b") // 2->b, 1->x (random order)
m.Put(1, "a") // 2->b, 1->a (random order)
_, _ = m.Get(2) // b, true
_, _ = m.Get(3) // nil, false
_ = m.Values() // []interface {}{"b", "a"} (random order)
_ = m.Keys() // []interface {}{1, 2} (random order)
m.Remove(1) // 2->b
m.Clear() // empty
m.Empty() // true
m.Size() // 0
}

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examples/hashset.go
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package examples
import "github.com/emirpasic/gods/sets/hashset"
func hashsetExample() {
set := hashset.New() // empty (keys are of type int)
set.Add(1) // 1
set.Add(2, 2, 3, 4, 5) // 3, 1, 2, 4, 5 (random order, duplicates ignored)
set.Remove(4) // 5, 3, 2, 1 (random order)
set.Remove(2, 3) // 1, 5 (random order)
set.Contains(1) // true
set.Contains(1, 5) // true
set.Contains(1, 6) // false
_ = set.Values() // []int{5,1} (random order)
set.Clear() // empty
set.Empty() // true
set.Size() // 0
}

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examples/linkedliststack.go
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package examples
import lls "github.com/emirpasic/gods/stacks/linkedliststack"
func linkedliststackExample() {
stack := lls.New() // empty
stack.Push(1) // 1
stack.Push(2) // 1, 2
_, _ = stack.Peek() // 2,true
_, _ = stack.Pop() // 2, true
_, _ = stack.Pop() // 1, true
_, _ = stack.Pop() // nil, false (nothing to pop)
stack.Push(1) // 1
stack.Clear() // empty
stack.Empty() // true
stack.Size() // 0
}

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examples/redblacktree.go
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package examples
import (
"fmt"
rbt "github.com/emirpasic/gods/trees/redblacktree"
)
func redblacktreeExample() {
tree := rbt.NewWithIntComparator() // empty(keys are of type int)
tree.Put(1, "x") // 1->x
tree.Put(2, "b") // 1->x, 2->b (in order)
tree.Put(1, "a") // 1->a, 2->b (in order, replacement)
tree.Put(3, "c") // 1->a, 2->b, 3->c (in order)
tree.Put(4, "d") // 1->a, 2->b, 3->c, 4->d (in order)
tree.Put(5, "e") // 1->a, 2->b, 3->c, 4->d, 5->e (in order)
tree.Put(6, "f") // 1->a, 2->b, 3->c, 4->d, 5->e, 6->f (in order)
fmt.Println(tree)
//
// RedBlackTree
// │ ┌── 6
// │ ┌── 5
// │ ┌── 4
// │ │ └── 3
// └── 2
// └── 1
_ = tree.Values() // []interface {}{"a", "b", "c", "d", "e", "f"} (in order)
_ = tree.Keys() // []interface {}{1, 2, 3, 4, 5, 6} (in order)
tree.Remove(2) // 1->a, 3->c, 4->d, 5->e, 6->f (in order)
fmt.Println(tree)
//
// RedBlackTree
// │ ┌── 6
// │ ┌── 5
// └── 4
// │ ┌── 3
// └── 1
tree.Clear() // empty
tree.Empty() // true
tree.Size() // 0
}

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examples/treemap.go
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package examples
import "github.com/emirpasic/gods/maps/treemap"
func treemapExample() {
m := treemap.NewWithIntComparator() // empty (keys are of type int)
m.Put(1, "x") // 1->x
m.Put(2, "b") // 1->x, 2->b (in order)
m.Put(1, "a") // 1->a, 2->b (in order)
_, _ = m.Get(2) // b, true
_, _ = m.Get(3) // nil, false
_ = m.Values() // []interface {}{"a", "b"} (in order)
_ = m.Keys() // []interface {}{1, 2} (in order)
m.Remove(1) // 2->b
m.Clear() // empty
m.Empty() // true
m.Size() // 0
}

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examples/treeset.go
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package examples
import "github.com/emirpasic/gods/sets/treeset"
func treesetExample() {
set := treeset.NewWithIntComparator() // empty
set.Add(1) // 1
set.Add(2, 2, 3, 4, 5) // 1, 2, 3, 4, 5 (in order, duplicates ignored)
set.Remove(4) // 1, 2, 3, 5 (in order)
set.Remove(2, 3) // 1, 5 (in order)
set.Contains(1) // true
set.Contains(1, 5) // true
set.Contains(1, 6) // false
_ = set.Values() // []int{1,5} (in order)
set.Clear() // empty
set.Empty() // true
set.Size() // 0
}
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