is it safe for a woman to travel alone in HK? i would like to stay there for a vacation

Oh, generally speaking, you don't need to worry about the safety problem. Just do not go to the places off the beaten track.
Most local people are friendly and outgoing. You can get along with them well.
And the nightlife in there is interesting and abundant.
Have a good journey!

Presuming you excercise the normal caution you would in any big city then you are unlikely to have problems - I have visited 2 or 3 times a year for the last 4 years or so and never had a problem

Annie