A javascript multiset with O(logN) insert , delete and Query.

Set.coffee

class Set
	constructor :(array=[])->
		@ary = array
		@pos = {}
		for value,key in @ary
			if @pos.hasOwnProperty value
				@pos[value].push key
			else
				@pos[value] = [key]

	insert :(element)->
		@ary.push element
		if @pos.hasOwnProperty element
			@pos[element].push @ary.length-1
		else
			@pos[element] = [@ary.length-1]

	remove :(element)->
		#console.log "remove " + element
		return unless @pos.hasOwnProperty element
		effection = {}
		for p in @pos[element]
			if (p == @ary.length-1)
				@ary.pop()
			else

				@ary[p] = @ary[@ary.length-1]
				effection[@ary[p]] = {} unless effection.hasOwnProperty @ary[p] 
				effection[@ary[p]][@ary.length-1] = p
				@ary.pop()
		delete @pos[element]
		#console.log(effection)
		for key,value of effection
			for k,v of @pos[key]
				# console.log("set " + @pos[key][k] + " to " +value[v] )
				@pos[key][k] = value[v] if value[v] != null
		0

	size : ->
		@ary.length

	getValue : (k)->
		@ary[k]

	getKey : (v)->
		@pos[v]

exports.Set = Set