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Cross a Rope Bridge in 17 minutes

rope-bridgeFour people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for seventeen minutes. The bridge is too dangerous to cross without a flashlight, and it’s only strong enough to support two people at any given time.
Each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the slow poke takes 10 minutes to cross. How do the campers make it across in 17 minutes?

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Posted by on Aug 10th, 2009 and filed under Discussions. You can follow any responses to this entry through the RSS 2.0. You can skip to the end and leave a response. Pinging is currently not allowed.

6 Responses for “Cross a Rope Bridge in 17 minutes”

  1. mo says:

    The 1 minute carries the 10 minute (1 minute)
    comes back (2 minutes)
    1 minute carries the 5 minute (3 minutes)
    comes back (4 minutes)
    1 minute walks with the 2 minute as the 2 minute holds the flashlight coz the 1 minute is tired as heck (6 minutes sharp)

    The flashlight is good for another 11 minutes Sharp. whats the riddle? too much over-engineered answers. The riddle needs more detail.

  2. Luke says:

    very nice dwayne
    1 and 2 – 2mins
    1 returns – 3mins

    5 and 10 – 13mins
    2 returns – 15mins

    1 and 2 – 17mins SHARP

    very nice, had this problem in my book in my algorithms class, book by Levitiin

  3. Allen says:

    1 and 2 cross, 1 returns (3 minutes)
    5 and 10 cross, 2 returns (15 minutes)
    1 and 2 cross (17 minutes)

  4. Ansgar John says:

    5 and 10 go across (Elapsed time 10 minutes). They throw the flashlight back to 1 and 2. (Elapsed time 10 minutes 10 seconds). 1 and 2 cross. (Elapsed time time 12 minutes 10 seconds)

  5. Dwayne says:

    1 and 2 go across witih the flashlight, 1 returns (Elapsed time 3 minutes.)
    5 and 10 go across (13 minutes), give the flashlight to 2. 2 returns (15 minutes). 2 and 1 cross (17 minutes).
    Then 10 realizes he has extra batteries in his pocket!

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