Given two number N,M.Count the number of pair(i,j) such that LCM(i,j)=i*j.Here M,N<=10^9 and min(M,N)=10^6. How can I do this?
Given two number N,M.Count the number of pair(i,j) such that LCM(i,j)=i*j.Here M,N<=10^9 and min(M,N)=10^6. How can I do this?
№ | 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 | 174 |
2 | awoo | 164 |
3 | adamant | 163 |
4 | TheScrasse | 159 |
5 | nor | 157 |
6 | maroonrk | 155 |
7 | -is-this-fft- | 152 |
8 | Petr | 146 |
8 | orz | 146 |
10 | BledDest | 145 |
Название |
---|
lcm(i, j) = i * j, when gcd(i, j) = 1.
so problem is -> how many pairs (i, j) such that gcd(i, j) = 1.
we can calculate it in min(n, m) with mebius function.
answer[i] = m[i] * f[i], where m[i] — value of mebius function(i), f[i] = function returning answer for i. in this problem it's (M / i) * (N / i)