| № | Пользователь | Рейтинг |
|---|---|---|
| 1 | tourist | 3757 |
| 2 | jiangly | 3647 |
| 3 | Benq | 3581 |
| 4 | orzdevinwang | 3570 |
| 5 | Geothermal | 3569 |
| 5 | cnnfls_csy | 3569 |
| 7 | Radewoosh | 3509 |
| 8 | ecnerwala | 3486 |
| 9 | jqdai0815 | 3474 |
| 10 | gyh20 | 3447 |
| Страны | Города | Организации | Всё → |
| № | Пользователь | Вклад |
|---|---|---|
| 1 | maomao90 | 171 |
| 2 | awoo | 164 |
| 2 | adamant | 164 |
| 4 | TheScrasse | 159 |
| 5 | nor | 155 |
| 6 | maroonrk | 154 |
| 7 | -is-this-fft- | 152 |
| 8 | Petr | 147 |
| 9 | orz | 146 |
| 10 | pajenegod | 145 |
Given a sequence a1, a2, ..., aN. Count the number of triples (i, j, k) such that 1 ≤ i < j < k ≤ N and GCD(ai, aj, ak) = 1. Here GCD stands for the Greatest Common Divisor.
http://www.codechef.com/LTIME13/problems/COPRIME3
the editorial is very difficult to understand,,isn't there any other methods??
Explicit introduction of mobius function in the editorial is unnecessary. Do you know the inclusion-exclusion principle?
no,i don't know how to use in coding,,i just know the mathematical definition @pompon any help will be great for this noob :)
Here you have a tutorial on how to apply inclusion-exclusion principle in general: http://apps.topcoder.com/forums/?module=Thread&threadID=685138&start=0