trip planner problem

"what will be a best approach for solving this"
The input is the set of flights between various cities. It is given as a file. Each line of the file contains “city1 city2 departure-time arrival-time flight-no. price” This means that there is a flight called “flight-no” (which is a string of the form XY012) from city1 to city2 which leaves city1 at time “departure-time” and arrives city2 at time “arrival-time”. Further the price of this flight is “price” which is a poitive integer. All times are given as a string of 4 digits in the 24hr format e.g. 1135, 0245, 2210. Assume that all city names are integers between 1 and a number N (where N is the total number of cities).

Note that there could be multiple flights between two cities (at different times).

The query that you have to answer is: given two cities “A” and “B”, times “t1”, “t2”, where t1 < t2, find the cheapest trip which leaves city “A” after time “t1” and arrives at city “B” before time “t2”. A trip is a sequence of flights which starts at A after time t1 and ends at B before time t2. Further, the departure time from any transit (intermediate) city C is at least 30 mins after the arrival at C

not found it covers mostly
codechef trick

not found it covers mostly
codechef trick

kindly specify the constraints of the possible input…this will give an insight to the expected efficiency of the solution…

#Will some one flag this as spam. I ran out of flags for today flgging this guys spams ( currently, he has 7 spams )

#Will some one flag this as spam. I ran out of flags for today flgging this guys spams ( currently, he has 7 spams )