UA 772 then DL 2253 at LAX
Beijing → Los Angeles → Las Vegas
Timetable, Los Angeles time
07:55UA 772 from Beijing at the gate
07:35DL 2253 to Las Vegas leaves the gate
23 h 40 apart on the timetable, overnight
DL 2253 leaves 23 h 40 after UA 772 arrives on the timetable: more than half a day, so not a connection we count.