Here is Lester Young's "Gigantic blues":
Question: what is the style of this song? Is it swing or bebop?
In my opinion this is more akin to bebop than swing. Tempo, improvisational style, and combo instrumentation are more in line with the bebop tradition (ala Charlie Parker, Dizzy Gillespie, early Miles Davis) than the swing tradition (e.g. Basie). That said, he was a member of Basie's band and it's difficult to deny those roots even listening to this tune objectively. Again my opinion: 85% bebop and 15% swing. How's that? :)