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Greedy

Chen
November 01, 2022

 Greedy

Chen

November 01, 2022
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  1. Activity Selection: Shortest
    Shortest duration does not work:
    47 / 55

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  2. Activity Selection: First Start
    Earliest start time doesn’t work either:
    48 / 55

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  3. Activity Selection: Fewest Overlaps
    Fewest overlaps doesn’t work either:
    49 / 55

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  4. Activity Selection: Shortest Delay
    Nor shortest delay to next activity:
    50 / 55

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  5. Activity Selection: Earliest End Time
    Earliest end time looks good:
    Note there are equally good alternatives here, but nothing
    better.
    But one example does not convince us..
    51 / 55

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  6. Refute Maleficent’s Claim
    Ok Maleficient,...
    I We want you to think about the first activity you picked that
    we did not.
    I Can you just swap it out with one of ours that overlaps with
    it?
    I If so, just do that (you aren’t getting any extra benefit).
    I Repeat this swapping until the answer is no...
    53 / 55

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  7. Refute Maleficent’s Claim
    So now we have...
    I But we can’t just swap out Maleficent’s activity for ours, so
    the picture needs to look more like this:
    Because Maleficent needs some other activity in her
    choices that conflicts with ours (so she can’t just swap)
    I But for that to happen, her activity has to end earlier than
    ours—but we picked greedily based on end time!
    54 / 55

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