I was giving this hiring contest ( already over ). I am stuck at this question. Needed some help
# | User | Rating |
---|---|---|
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 |
# | User | Contrib. |
---|---|---|
1 | Um_nik | 164 |
2 | maomao90 | 160 |
3 | -is-this-fft- | 159 |
4 | atcoder_official | 158 |
4 | awoo | 158 |
4 | cry | 158 |
7 | adamant | 155 |
8 | nor | 154 |
9 | TheScrasse | 153 |
10 | maroonrk | 152 |
I was giving this hiring contest ( already over ). I am stuck at this question. Needed some help
Name |
---|
The only conclusion I was able to reach is that for any query L, R, a and b, let g be the gcd of a, b. Then
But it is just an optimization of bruteforce.
Since $$$max(a, b) \le 10^3$$$, an optimization can be to build segment tree over the array, the nodes of which, will contain $$$10^3$$$ values, each corresponding to the required range sum as the gcd varies from $$$1$$$ to $$$1000$$$.
Update is $$$O(M \cdot \log N)$$$ and query is $$$O(\log N)$$$ with $$$O(N \cdot M)$$$ memory, where $$$M = max(a, b)$$$.
Since $$$M \le 10^3$$$, this could probably be fit into TL depending on how much it is.