Codeforces Round 814 (Div. 1)
C
Tonya and Burenka-179
Codeforces
2400
原题
← BD →
翻译中…

Tonya was given an array of $a$ of length $n$ written on a postcard for his birthday. For some reason, the postcard turned out to be a cyclic array, so the index of the element located strictly to the right of the $n$-th is $1$. Tonya wanted to study it better, so he bought a robot "Burenka-179".

翻译中…

A program for Burenka is a pair of numbers $(s, k)$, where $1 \leq s \leq n$, $1 \leq k \leq n-1$. Note that $k$ cannot be equal to $n$. Initially, Tonya puts the robot in the position of the array $s$. After that, Burenka makes exactly $n$ steps through the array. If at the beginning of a step Burenka stands in the position $i$, then the following happens:

翻译中…
  1. The number $a_{i}$ is added to the usefulness of the program.
  2. "Burenka" moves $k$ positions to the right ($i := i + k$ is executed, if $i$ becomes greater than $n$, then $i := i - n$).
翻译中…

Help Tonya find the maximum possible usefulness of a program for "Burenka" if the initial usefulness of any program is $0$.

翻译中…

Also, Tony's friend Ilyusha asks him to change the array $q$ times. Each time he wants to assign $a_p := x$ for a given index $p$ and a value $x$. You need to find the maximum possible usefulness of the program after each of these changes.

翻译中…

Input

翻译中…

The first line contains a single integer $t$ ($1 \le t \le 10^4$) is the number of test cases. The description of the test cases follows.

翻译中…

The first line of each test case contains two integers $n$ and $q$ ($2 \le n \le 2 \cdot 10^5$, $0 \le q \le 2 \cdot 10^5$).

翻译中…

The second line of each test case contains $n$ integers $a_1, a_2, \ldots, a_n$ ($1 \le a_i \le 10^9$) — elements of the array.

翻译中…

The following $q$ lines contain changes, each of them contains two integers $p$ and $x$ ($1 \leq p \leq n$, $1 \leq x \leq 10^9$), meaning you should assign $a_p := x$.

翻译中…

It is guaranteed that the sum of $n$ and the sum of $q$ over all test cases do not exceed $2 \cdot 10^5$.

翻译中…

Output

翻译中…

For each test case, output $q+1$ numbers — the maximum usefulness of a program initially and after each of the changes.

翻译中…

Note

翻译中…

In the first test case, initially and after each request, the answer is achieved at $s = 1$, $k = 1$ or $s = 2$, $k = 1$.

翻译中…

In the second test case, initially, the answer is achieved when $s = 1$, $k = 2$ or $s = 3$, $k = 2$. After the first request, the answer is achieved at $s = 2$, $k = 2$ or $s = 4$, $k = 2$.

翻译中…

样例

Input #1
4
2 1
1 2
1 3
4 4
4 1 3 2
2 6
4 6
1 1
3 11
9 3
1 7 9 4 5 2 3 6 8
3 1
2 1
9 1
6 3
1 1 1 1 1 1
1 5
4 4
3 8
Output #1
3
5
14
16
24
24
24
57
54
36
36
6
18
27
28
InputCopy OutputCopy
题目信息
题号
1718C
时间限制
3 s
内存限制
256 MB
标签
数据结构
贪心
数学
数论

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。