$ swipl flights.prolog 
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For help, use ?- help(Topic). or ?- apropos(Word).

?- route(sjc, phl, [], DT, AT, Flights, TotalCost). 
false.

?- route(sfo, sjc, [], DT, AT, Flights, TotalCost).
DT = 8:0,
AT = 11:5,
Flights = [sfo, lax, sjc],
TotalCost = 237.5 ;
DT = 8:0,
AT = 19:15,
Flights = [sfo, lax, sjc],
TotalCost = 236.11 ;
DT = 12:40,
AT = 19:15,
Flights = [sfo, lax, sjc],
TotalCost = 239.22000000000003 ;
false.

?- route(aus, phl, [], DT, AT, Flights, TotalCost).
DT = 7:45,
AT = 11:56,
Flights = [aus, phl],
TotalCost = 427.47 ;
DT = 6:29,
AT = 12:28,
Flights = [aus, ewr, phl],
TotalCost = 656.11 ;
DT = 6:29,
AT = 15:23,
Flights = [aus, ewr, phl],
TotalCost = 656.11 ;
false.

?- route(ewr, lax, [], DT, AT, Flights, TotalCost).
DT = 9:5,
AT = 12:20,
Flights = [ewr, lax],
TotalCost = 292.47 ;
DT = 5:25,
AT = 20:40,
Flights = [ewr, lax],
TotalCost = 292.47 ;
DT = 9:0,
AT = 14:20,
Flights = [ewr, aus, lax],
TotalCost = 712.35 ;
DT = 9:0,
AT = 21:50,
Flights = [ewr, aus, sfo, lax],
TotalCost = 709.3199999999999 ;
DT = 6:59,
AT = 21:50,
Flights = [ewr, phl, sfo, lax],
TotalCost = 1273.4 ;
DT = 11:35,
AT = 21:50,
Flights = [ewr, phl, sfo, lax],
TotalCost = 1273.4 ;
DT = 14:29,
AT = 21:50,
Flights = [ewr, phl, sfo, lax],
TotalCost = 1273.4 ;
DT = 7:30,
AT = 14:0,
Flights = [ewr, sfo, lax],
TotalCost = 402.82 ;
DT = 7:30,
AT = 21:50,
Flights = [ewr, sfo, lax],
TotalCost = 383.37 ;
DT = 10:30,
AT = 21:50,
Flights = [ewr, sfo, lax],
TotalCost = 383.37 ;
DT = 16:11,
AT = 21:50,
Flights = [ewr, sfo, lax],
TotalCost = 383.37 ;
false.

?-