Congratulations and congratulations Korea! Again!
China as reliable as ever. And congratulations India on picking up the pace going the other way - out of the top-50 now. Behind Saudi, Bangladesh, Peru..
| Country | Team size | P1 | P2 | P3 | P4 | P5 | P6 | Total | Rank | Awards | Leader | Deputy leader | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| All | M | F | G | S | B | HM | |||||||||||
| Republic of Korea | 6 | 5 | 1 | 42 | 39 | 1 | 42 | 22 | 24 | 170 | 1 | 6 | 0 | 0 | 0 | Yongjin Song | Suyoung Choi |
| People's Republic of China | 6 | 6 | 42 | 25 | 0 | 42 | 19 | 31 | 159 | 2 | 5 | 1 | 0 | 0 | Yijun Yao | Sihui Zhang | |
| Vietnam | 6 | 6 | 42 | 36 | 0 | 42 | 21 | 14 | 155 | 3 | 4 | 1 | 1 | 0 | Anh Vinh Lê | Bá Khánh Trình Lê | |
| United States of America | 6 | 6 | 42 | 29 | 0 | 42 | 23 | 12 | 148 | 4 | 3 | 3 | 0 | 0 | Po-Shen Loh | Brian Lawrence | |
| Islamic Republic of Iran | 6 | 6 | 42 | 32 | 0 | 42 | 17 | 9 | 142 | 5 | 2 | 3 | 1 | 0 | Omid Hatami Varzaneh | Seyed Hesam Firouzi | |
| Japan | 6 | 6 | 41 | 21 | 0 | 42 | 23 | 7 | 134 | 6 | 2 | 2 | 2 | 0 | Yasuo Morita | Keiko Tasaki | |
| Singapore | 6 | 6 | 42 | 26 | 0 | 37 | 22 | 4 | 131 | 7 | 2 | 1 | 2 | 1 | Yan Loi Wong | Xinghuan Ai | |
| Contestant [♀♂][←] | Country | P1 | P2 | P3 | P4 | P5 | P6 | Total | Rank | Award |
|---|---|---|---|---|---|---|---|---|---|---|
| Amirmojtaba Sabour | Islamic Republic of Iran | 7 | 7 | 0 | 7 | 7 | 7 | 35 | 1 | Gold medal |
| Yuta Takaya | Japan | 7 | 7 | 0 | 7 | 7 | 7 | 35 | 1 | Gold medal |
| Hữu Quốc Huy Hoàng | Vietnam | 7 | 7 | 0 | 7 | 7 | 7 | 35 | 1 | Gold medal |
| Qiuyu Ren | People's Republic of China | 7 | 7 | 0 | 7 | 7 | 4 | 32 | 4 | Gold medal |
| Aleksandre Saatashvili | Georgia | 7 | 7 | 0 | 7 | 7 | 3 | 31 | 5 | Gold medal |
| James Lin | United States of America | 7 | 7 | 0 | 7 | 7 | 2 | 30 | 6 | Gold medal |
Are you, like me, wondering what was so tricky about Problem 3? (I'm clueless, ICYW). Nice variation on the curve of pursuit problem I first saw in Brilliant Tutorials (lifted from Irodov).
Problem 3. A hunter and an invisible rabbit play a game in the Euclidean plane. The rabbit’s starting point, A0, and the hunter’s starting point, B0, are the same. After n−1 rounds of the game, the rabbit is at point An−1 and the hunter is at point Bn−1.
In the n th round of the game, three things occur in order.
(i) The rabbit moves invisibly to a point An such that the distance between An−1 and An is exactly 1.
(ii) A tracking device reports a point Pn to the hunter. The only guarantee provided by the tracking device to the hunter is that the distance between Pn and An is at most 1.
(iii) The hunter moves visibly to a point Bn such that the distance between Bn−1 and Bn is exactly 1.
Is it always possible, no matter how the rabbit moves, and no matter what points are reported by the tracking device, for the hunter to choose her moves so that after 109 rounds she can ensure that the distance between her and the rabbit is at most 100?
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