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| Показать все ветки Спрятать все ветки Показать все сообщения Спрятать все сообщения | | Test 27????? Please!!! | ilya trofimov | 1911. Руины титанов: наперегонки с огнём | 24 янв 2013 18:52 | 1 | | | Anti-WA22 Test | bsu.mmf.team | 1911. Руины титанов: наперегонки с огнём | 8 ноя 2012 14:54 | 6 | This problem is not difficult. A lot of people got long sequences of WA#22 (as well as I did) because of one very stupid mistake. I hope this test will help to understand this mistake:
10 10 20 10 100 1 2012 10000
1
30 60
Answer: 15000.0000000 Thanks for the test. I get a different answer (and have WA22) -- 14000. To get your answer from my calculations you're either stopping the cart in the tunnel (which should never be necessary I think) or you're getting a different value for the time when the fire passes the end of the tunnel. I'm not sure where my mistake is. The cart clearly fully enters the tunnel at time 4, and the back of the fire passes the end of the tunnel at time 9 (the fire does not meet the cart before it fully enters the tunnel). 9-4=5. Covering 20 m over 5 seconds with initial velocity 10 requires deceleration of a = 2.4, which is 1.4 more than 1, thus 14000. I'm assuming the front of the cart can't enter the tunnel into the fire...
What's wrong with my reasoning?
Edited by author 01.11.2012 12:30 With deceleration 2.4 after 5 seconds in the tunnel a velocity of the cart will be equal 10 - 2.4*5 = -2.
Oops :) Haha! That's funny. I just used "s = v * t - 1/2 a * t^2" but forgot to check whether it involved "backing up" :). Sorry to Soren and Alba for barbecuing you before backing you up into the safety of the tunnel! I'm sure they'll forgive you. You are not the first who does that ;)
It's very funny that this fact didn't allow to solve the problem anybody who tried to do it during the contest.
Edited by author 02.11.2012 12:14 At long last, AC. Lots of little details to pay attention to in this one! | | Please, give some tests. (-) | Yermak | 1911. Руины титанов: наперегонки с огнём | 28 окт 2012 10:55 | 1 | | | Is it possible to enter the side tunnels several times? | BSU_1 | 1911. Руины титанов: наперегонки с огнём | 21 окт 2012 12:10 | 2 | It doesn't look like it can be cleared out from a problem description. If so, does the speed of a cart remains equal 'v' after tunnel exiting, or the same, as at the end of a side tunnel? NO
"Meanwhile, the wall of fire continued to approach the cart. Time was running out, and a plan had to be developed fast. WIZARDS CAN TURN TO A SIDE TUNNEL ONLY ONCE BECAUSE THE CART IS VERY OLD AND NOT SUITED WELL FOR MAKING TURNS. But which tunnel to use?"
Edited by author 21.10.2012 12:13 |
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