Recently, I was trying to solve a problem. To solve that I shall have to solve a sub problem. The sub problem is:
I will be provided some values. I want to find number of pairs possible for that set of values who have gcd>1
Can anyone suggest an efficient approach? I just want you to give me hints so that I can start from that point of view and move forward.
| № | Пользователь | Рейтинг |
|---|---|---|
| 1 | tourist | 3690 |
| 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 | 173 |
| 2 | awoo | 164 |
| 3 | adamant | 163 |
| 4 | TheScrasse | 160 |
| 5 | nor | 157 |
| 6 | maroonrk | 155 |
| 7 | -is-this-fft- | 152 |
| 8 | Petr | 146 |
| 8 | orz | 146 |
| 10 | pajenegod | 145 |
if the values are $$$\le 10^6$$$, you can try to check $$$d,2d,3d...$$$ for each $$$2\le d \le 10^6$$$
Can you please elaborate a little bit?
make the array $$$cnt$$$, where $$$cnt_d$$$ means the number of occurrences of value $$$d$$$ in the array.
And when you check $$$d$$$ and $$$2d$$$, whose gcd is $$$2$$$, the number of pairs they make is $$$cnt_d*cnt_{2d}$$$