hello i am writing this blog because i asked a question but havent got asnwer for it, please explain me why do we need to use segment tree to calculate sums, why cant we just use c++ operator + (read more about this operator here — https://www.w3schools.com/cpp/cpp_operators.asp)
| № | Пользователь | Рейтинг |
|---|---|---|
| 1 | tourist | 3757 |
| 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 | 171 |
| 2 | awoo | 164 |
| 3 | adamant | 163 |
| 4 | TheScrasse | 159 |
| 5 | maroonrk | 155 |
| 6 | nor | 154 |
| 7 | -is-this-fft- | 152 |
| 8 | Petr | 147 |
| 9 | orz | 145 |
| 10 | pajenegod | 144 |
I hope you're kidding
no i am not kidding please explain
how you became Blue??
i have used + operator
The + operator in general won't give you the sum of an array over an index range [l...r] in log(N) time. A segment tree will.
yes but + operator is O(1) while segment tree is logN, so we should use + operator, isnt it?
Because you need to apply the + operator (r — l) = O(n) times to find the sum from l to r. With a segment tree, you can do this in O(log N)
r — l = n it means that r — l — n = 0 so the complexity is O(0), right?
i am trying to solve this problem — https://codeforces.com/problemset/problem/409/H?locale=ru
but my segment tree solution fails
This problem is troll; look at the result of the submission when I use the plus operator: https://codeforces.com/contest/409/submission/70091573
Is it just me, or did the language of my codeforces suddenly change to Russian?
i think your solution has failed, because you used + operator instead of segment tree
Its big brain time!
yeah it's your time