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Editorial Team
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Asked: 2026-05-28T07:37:19+00:00

I needed some help/pointers on a homework problem. I would really appreciate it if

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I needed some help/pointers on a homework problem. I would really appreciate it if someone could point me in the right direction on how to go about solving this problem 🙂

Assignment

“An angry bird named Mo is flying a long journey to exact his revenge
on the pigs. To save energy for the fight, the bird will take
advantage of jet streams that will lower his flying energy
consumption. Before the flight, BirdHQ gave the bird an input file in
the following format:

  1. First line contains only 1 integer, which is the constant energy it takes to fly 1 mile WITHOUT jet streams.
  2. Every subsequent line contains 3 space-separated integers: the start mile marker of the jet stream, the end mile marker of the jet
    stream, and lastly an integer denoting the overall energy needed to
    fly that jet stream’s distance.

For instance, the line “3 7 12″ means it takes 12 energy units to fly
the 4 miles between miles 3 and 7.

Note that jet streams can overlap, but the bird cannot be on more than
one jet stream at a time, and it cannot fly partial jet streams.

For simplicity, consider the end mile marker of the farthest jet
stream as the end of the journey.

Write a python program that takes in an input file “jetstreams.txt” to
plan out the optimal sequence of jet streams Mo should fly on to
minimize his energy consumption throughout the entire journey. All
integers in the input file are non-negative. As output, print out the
mininum total energy and a list of tuples denoting the jet streams’
endpoints.

For example, given the sample jetstreams.txt, the minimum total energy
needed to fly all 24 miles is 352 energy units, and the optimal
sequence of jet streams is [(0,5), (6,11), (14,17), (19,24)].”

jetstreams.txt

50
0 5 10
1 3 5
3 7 12
6 11 20
14 17 8
19 24 14
21 22 2

Would this be anything like solving the shortest path of a graph?

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1 Answer

  1. Editorial Team

    Yes.

    You have a “don’t use the jetstream at all” path, which consists of vertices numbered 0, 1, 3, 5, 6, 7, 11, 14, 17, 19, 21, 22, 24. The edges which join each of these vertices has a “weight” of 50* the distance – so the 0->1 edge is weighted 50, the 1->3 edge is weighted 100, etc.

    Then, you have additional edges representing the jetstreams – one from 0->5 weighted 10, one from 1->3 weighted 5, etc.

    Together, these form a directed acyclic graph (a DAG).

    Now you have that, you can apply the usual graph traversal techniques to find the “cheapest” route from vertex 0 to vertex 24.

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