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https://github.com/ryszard/goskiplist

A skip list implementation in Go
https://github.com/ryszard/goskiplist

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A skip list implementation in Go

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README 

        
About

=====



This is a library implementing skip lists for the Go programming

language (http://golang.org/).



Skip lists are a data structure that can be used in place of

balanced trees. Skip lists use probabilistic balancing rather than

strictly enforced balancing and as a result the algorithms for

insertion and deletion in skip lists are much simpler and

significantly faster than equivalent algorithms for balanced trees.



Skip lists were first described in

[Pugh, William (June 1990)](ftp://ftp.cs.umd.edu/pub/skipLists/skiplists.pdf). "Skip

lists: a probabilistic alternative to balanced trees". Communications

of the ACM 33 (6): 668–676



[![Build Status](https://travis-ci.org/ryszard/goskiplist.png?branch=master)](https://travis-ci.org/ryszard/goskiplist)



Installing

==========



    $ go get github.com/ryszard/goskiplist/skiplist



Example

=======



```go

package main



import (

	"fmt"

	"github.com/ryszard/goskiplist/skiplist"

)



func main() {

	s := skiplist.NewIntMap()

	s.Set(7, "seven")

	s.Set(1, "one")

	s.Set(0, "zero")

	s.Set(5, "five")

	s.Set(9, "nine")

	s.Set(10, "ten")

	s.Set(3, "three")



	firstValue, ok := s.Get(0)

	if ok {

		fmt.Println(firstValue)

	}

	// prints:

	//  zero



	s.Delete(7)



	secondValue, ok := s.Get(7)

	if ok {

		fmt.Println(secondValue)

	}

	// prints: nothing.



	s.Set(9, "niner")



	// Iterate through all the elements, in order.

	unboundIterator := s.Iterator()

	for unboundIterator.Next() {

		fmt.Printf("%d: %s\n", unboundIterator.Key(), unboundIterator.Value())

	}

	// prints:

	//  0: zero

	//  1: one

	//  3: three

	//  5: five

	//  9: niner

	//  10: ten



	for unboundIterator.Previous() {

		fmt.Printf("%d: %s\n", unboundIterator.Key(), unboundIterator.Value())

	}

	//  9: niner

	//  5: five

	//  3: three

	//  1: one

	//  0: zero



	boundIterator := s.Range(3, 10)

	// Iterate only through elements in some range.

	for boundIterator.Next() {

		fmt.Printf("%d: %s\n", boundIterator.Key(), boundIterator.Value())

	}

	// prints:

	//  3: three

	//  5: five

	//  9: niner



	for boundIterator.Previous() {

		fmt.Printf("%d: %s\n", boundIterator.Key(), boundIterator.Value())

	}

	// prints:

	//  5: five

	//  3: three



	var iterator skiplist.Iterator



	iterator = s.Seek(3)

	fmt.Printf("%d: %s\n", iterator.Key(), iterator.Value())

	// prints:

	//  3: three



	iterator = s.Seek(2)

	fmt.Printf("%d: %s\n", iterator.Key(), iterator.Value())

	// prints:

	//  3: three



  iterator = s.SeekToFirst()

  fmt.Printf("%d: %s\n", iterator.Key(), iterator.Value())

  // prints:

  //  0: zero



  iterator = s.SeekToLast()

  fmt.Printf("%d: %s\n", iterator.Key(), iterator.Value())

  // prints:

  //  10: ten



  // SkipList can also reduce subsequent forward seeking costs by reusing the

  // same iterator:



  iterator = s.Seek(3)

	fmt.Printf("%d: %s\n", iterator.Key(), iterator.Value())

	// prints:

	//  3: three



  iterator.Seek(5)

	fmt.Printf("%d: %s\n", iterator.Key(), iterator.Value())

	// prints:

	//  5: five

}

```



Full documentation

==================



Read it [online](http://godoc.org/github.com/ryszard/goskiplist/skiplist) or run



    $ go doc github.com/ryszard/goskiplist/skiplist



Other implementations

=====================



This list is probably incomplete.



  * https://github.com/huandu/skiplist

  * https://bitbucket.org/taruti/go-skip/src

  * http://code.google.com/p/leveldb-go/source/browse/leveldb/memdb/memdb.go

  (part of [leveldb-go](http://code.google.com/p/leveldb-go/))