Given N points. I want to find convex hull keeping collinear points. How should I prepare my initial sort function so that I don't have to make a right turn for points who are collinear? Example: 6 1 1 3 0 2 0 4 1 2 2 0 0 
Пожалуйста, прочтите новое правило об ограничении использования AI-инструментов.
→ Обратите внимание
→ Трансляции
→ Лидеры (рейтинг)
| № | Пользователь | Рейтинг |
|---|---|---|
| 1 | tourist | 4009 |
| 2 | jiangly | 3839 |
| 3 | Radewoosh | 3646 |
| 4 | jqdai0815 | 3620 |
| 4 | Benq | 3620 |
| 6 | orzdevinwang | 3612 |
| 7 | Geothermal | 3569 |
| 7 | cnnfls_csy | 3569 |
| 9 | ecnerwala | 3494 |
| 10 | Um_nik | 3396 |
| Страны | Города | Организации | Всё → |
→ Лидеры (вклад)
| № | Пользователь | Вклад |
|---|---|---|
| 1 | Um_nik | 164 |
| 2 | maomao90 | 160 |
| 3 | -is-this-fft- | 159 |
| 4 | atcoder_official | 158 |
| 4 | cry | 158 |
| 4 | awoo | 158 |
| 7 | adamant | 155 |
| 8 | nor | 154 |
| 9 | TheScrasse | 153 |
| 10 | maroonrk | 152 |
→ Найти пользователя
→ Прямой эфир
Codeforces (c) Copyright 2010-2024 Михаил Мирзаянов
Соревнования по программированию 2.0
Время на сервере: 02.10.2024 20:22:36 (i1).
Десктопная версия, переключиться на мобильную.
При поддержке
I don't know why that image is being failed to load. Anyway this is the link of the image: http://postimg.org/image/r8enk3er5/
I'm sure It's impossible to sort points in folowing order.If you add (2, 0.5) it will be a big question about order. I think the best idea is to find points using classical algorithm and then add points that lie between adjecent points on convex hull. It will take about O(n*n log n) using set, but i hope it can be solved with faster way.
Well, actually it's possible to sort the points beforehand. If we sort the points by their angle and then by their distance from (0, 0) assuming that (0, 0) is the leftmost-bottom point from the set, then the order will be correct everywhere except for the last edge of the convex hull. That is the points on all edges of the convex hull except for the last one will be in the correct order and the points located on the last edge will be reversed. Notice that the last point in the sorted list will always belong to the convex hull which means we can just reverse the order of all points having the same angle as the last one (the one with the largest angle).
Well, I really missed this. Sounds correct, thank you!
NVM