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https://texercises.com/exercise/four-people-on-a-rickety-bridge/
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Exercise:
Four people need to cross a rickety bridge at night. Unfortunately they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: pqmin pqmin pqmin and pqmin. What is the shortest time needed for all four of them to cross the bridge?

Solution:
The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? + + + + pqmin Is that it? No. That would make this question too simple even as a warm up question. Let’s brainstorm a little further. To reduce the amount of time we should find a way for and to go together. If they cross together then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have one waiting on the other side to bring the torch back. Aha we are getting closer. The fastest way to get one across and be back is to use two to usher one across. So let’s put all this together. compactitem item and go cross item comes back item and go across item comes back item and go across done compactitem Total time: + + + + pqmin
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\(\LaTeX\)-Code
Exercise:
Four people need to cross a rickety bridge at night. Unfortunately they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: pqmin pqmin pqmin and pqmin. What is the shortest time needed for all four of them to cross the bridge?

Solution:
The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? + + + + pqmin Is that it? No. That would make this question too simple even as a warm up question. Let’s brainstorm a little further. To reduce the amount of time we should find a way for and to go together. If they cross together then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have one waiting on the other side to bring the torch back. Aha we are getting closer. The fastest way to get one across and be back is to use two to usher one across. So let’s put all this together. compactitem item and go cross item comes back item and go across item comes back item and go across done compactitem Total time: + + + + pqmin
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denken, denksel, google, interview, job, logic, logik, question, rätsel, think, thinkquest
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Difficulty
(4, default)
Points
3 (default)
Language
ENG (English)
Type
Both
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Link