Understanding doubt

#1

In the disused algorithm, when we have to take one flight almost Sir has taken the root First by train then flight and then train,
My doubt is We can also take the root as first flight then train and again take the train
So why we don’t take it the algorithm

#2

@Lovishbansal hey it is mentioned clearly in question actually we have followed up this approach:

  1. Apply dijsktra’s from src vertex considering only the train costs and let us call the shortest cost array from src vertex to every other vertex be costFromSrc[]; // SHORTEST TRAIN COST FROM SRC
  2. Apply dijsktra’s from destination vertex considering only the train costs and let us call the shortest cost array from destination vertex to every other vertex be costFromDest[]; // SHORTEST TRAIN COST FROM DEST
  3. Run two loops
int minFare = costFromSrc["destVertex"];
for(int i = 0; i < V; i++) {
   for(int k = 0; k < V; k++) {
       minFare = min(minFare, costFromSrc[i] + costFromDest[k] + flightFare[i][k]);
   }
}

What the above code do is for the flight between each i->k (i & k are vertices), if ((cost from src to i (through train) + cost from i to k through flight + cost from k to destination ) < minFare)
Then update minFare to be the least.

#3

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.