1 / 12

HKOI Senior Q2 - Igloo

HKOI Senior Q2 - Igloo. Ivan Li. Background. A peaceful sports event of innocent cute little penguins...... mercilessly destroyed by Big Bad Monsters!. In short. Single elimination tournament Tree structure Taller penguin wins In case of a tie, compare index Must not let monsters win!.

tess
Download Presentation

HKOI Senior Q2 - Igloo

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HKOI Senior Q2 - Igloo Ivan Li

  2. Background • A peaceful sports event of innocent cute little penguins...... • mercilessly destroyed by Big Bad Monsters!

  3. In short • Single elimination tournament • Tree structure • Taller penguin wins • In case of a tie, compare index • Must not let monsters win!

  4. Direct simulation • Stores the penguins in an array, and simulate the competition process • After some tedious typing work, you get 50%

  5. When there is no monsters • The tallest penguin wins • If tie, the lowest index • Hurrah! 20%!

  6. When monsters step in • They may beat the potential winners • Good news – monsters live in the same igloo. Their indexes are consecutive

  7. Observation 1 • When the monsters are not the tallest, we don’t have to be afraid of them • Just ignore them

  8. Observation 2 • When the monsters on the left subtree, all normal penguins in that subtree will be beaten. • Only consider the right subtree • Similar holds for right subtree

  9. Full Solution • Call the penguins on the left(right) of the monsters “the left(right) band”. • Find the largest subtree that is included in the bands • Lengths must be power of 2 • Which subtree survives longer? • The taller (larger) one • Tie – the right one • The tallest penguin in that subtree

  10. Full Solution

  11. Alternative solution • Maintain the start and end index of each igloo • Simulate the rounds • Calculate the boundaries • Match on the boundaries? • Who wins?

  12. Questions?

More Related