Question about music

Hi, I'm trying to identify some of the songs in this movie, particularly the song playing when Xiao Yong and Xiao Wu are walking around in the city and is played at night in the city when Xiao Wu has been arrested. And the song played when Xiao Wu and Meimei are dancing. (it's at the end of this trailer
http://www.youtube.com/watch?v=k4kLUNJTfl8 )