HashMap

class HashMap
	Entry = Struct.new :key,:value,:next
	def initialize 
		@table = [nil]*7
		@count = 0
	end
	def each
		for p in @table
			until p.nil?
				yield p.key, p.value
				p = p.next
			end
		end
	end
	def rehash
		new_table = [nil]*(@count*2+1)
		for p in @table
			until p.nil?
				q = p
				p = p.next
				index = q.key.hash % new_table.size 
				q.next = new_table[index]
				new_table[index] = q
			end
		end
		@table = new_table
		nil
	end
	def key? key
		index = key.hash % @table.size
		p = @table[index]
		until p.nil?
			return true if p.key==key
			p = p.next
		end
		false
	end
	def [] key
		index = key.hash % @table.size
		p = @table[index]
		until p.nil?
			break p.value if p.key==key
			p = p.next
		end
	end
	def []= key,value
		index = key.hash % @table.size
		p = @table[index]
		until p.nil?
			if p.key == key
				p.value = value
				return
			end
			p = p.next
		end
		rehash if @count>(@table.size*0.75)
		@table[index] = Entry.new key,value,@table[index]
		@count += 1
	end
	def delete key
		index = key.hash % @table.size
		p = @table[index]
		q = nil
		until p.nil?
			if p.key == key
				if q.nil?
					@table[index] = p.next
				else
					q.next = p.next
				end
				@count -= 1 
				return
			end
			q = p
			p = p.next
		end		
	end
end