Can anybody explain me the concept of difference array??
№ | Пользователь | Рейтинг |
---|---|---|
1 | tourist | 3880 |
2 | jiangly | 3669 |
3 | ecnerwala | 3654 |
4 | Benq | 3627 |
5 | orzdevinwang | 3612 |
6 | Geothermal | 3569 |
6 | cnnfls_csy | 3569 |
8 | jqdai0815 | 3532 |
9 | Radewoosh | 3522 |
10 | gyh20 | 3447 |
Страны | Города | Организации | Всё → |
№ | Пользователь | Вклад |
---|---|---|
1 | awoo | 161 |
2 | maomao90 | 160 |
3 | adamant | 156 |
4 | maroonrk | 153 |
5 | -is-this-fft- | 148 |
5 | SecondThread | 148 |
5 | atcoder_official | 148 |
8 | Petr | 147 |
9 | nor | 144 |
9 | TheScrasse | 144 |
Can anybody explain me the concept of difference array??
Название |
---|
given an array A[n], its difference array D is some array that satisfies D[i] = A[i] — A[i — 1] (for 1 < i <= N), and D[1] = A[1].
It can be used to perform range update queries of, for instance, adding some value x to all indicies from l to r. you create the difference array, then for each query "l r x", you perform D[l] += x, D[r + 1] -= x, and after all the queries you return to the normal array from it, by performing partial sum (A[1] = D[1], A[i] = A[i — 1] + D[i]) and you're done. Each query was in O(1) instead of O(N).