In a weighted tree, how to find for some node (u) the distance to another node (v) (answering Q queries effeiciently)? Constraints N <=10^3, Queries <=10^3
In a weighted tree, how to find for some node (u) the distance to another node (v) (answering Q queries effeiciently)? Constraints N <=10^3, Queries <=10^3
| № | 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 | pajenegod | 145 |
Since N is small you can apply BFS starting from u in each query and print the distance of node v which will take O(n) time for each query. An efficient way to answer each query in O(logn) is using LCA which can be found in O(logn) using binary lifting.
I teach all these concepts with practice problems , here is the graph theory playlist where you can find this concept along with other concepts. https://www.youtube.com/playlist?list=PL2q4fbVm1Ik64I3VqbVGRfl_OgYzvzt9m hope this helps.