题目描述
Problem Description
Given two sequences $a$ and $b$ of length $2N$, where the $i$-th element is $a_i$ and $b_i$ respectively. Snuke is tasked with calculating the beauty of pairs of balanced parentheses sequences $(s, t)$ using these sequences. The beauty is calculated as follows:
- Initialize $X = 0$
- For all $i$ from $1$ to $2N$, if $s_i = t_i$, add $a_i$ to $X$; otherwise, add $b_i$ to $X$
- The final value of $X$ is the beauty of $(s, t)
You are given $Q$ queries to process sequentially. In the $i$-th query, update $a_{p_i}$ to $x_i$ and $b_{p_i}$ to $y_i$, then find the maximum possible beauty of a pair of balanced parentheses sequences.
In this problem, only the following are defined as balanced parentheses sequences:
- The empty string
- For a balanced parentheses sequence $s$, the string formed by concatenating
(, $s$, and)in this order - For balanced parentheses sequences $s$ and $t$, the string formed by concatenating $s$ and $t$ in this order
Input Format
The input is given from the standard input in the following format:
$ N $ $ Q $ $ a_1 $ $ a_2 $ $ ... $ $ a_{2N} $ $ b_1 $ $ b_2 $ $ ... $ $ b_{2N} $ $ p_1 $ $ x_1 $ $ y_1 $ $ : $ $ p_Q $ $ x_Q $ $ y_Q $
Output Format
Output the answers in $Q$ lines. The $i$-th line should contain the response to the $i$-th query.
Sample Input and Output
Sample Input #1
2 2
1 1 7 3
4 2 3 3
2 4 6
3 2 5
Sample Output #1
15
15
Sample Input #2
7 7
34 -20 -27 42 44 29 9 11 20 44 27 19 -31 -29
46 -50 -11 20 28 46 12 13 33 -22 -48 -27 35 -17
7 27 34
12 -2 22
4 -50 -12
3 -32 15
8 -7 23
3 -30 11
4 -2 23
Sample Output #2
311
312
260
286
296
292
327
Notes/Hints
Constraints
- $1 \leq N, Q \leq 10^5$
- $-10^9 \leq a_i, b_i, x_i, y_i \leq 10^9$
- $1 \leq p_i \leq 2N$
- All given inputs are integers
Partial Points
- For a dataset worth 200 points, $N \leq 5, Q \leq 10$ holds
- For a dataset worth 300 points, $ Q = 1 $ holds
Sample Explanation 1
- After the first query, $ a = (1, 4, 7, 3), b = (4, 6, 3, 3) $. When $(s, t) = (`()()`, `()()`) $, the beauty is $ 15 $, which is the maximum.
- After the second query, $ a = (1, 4, 2, 3), b = (4, 6, 5, 3) $. When $(s, t) = (`()()`, `(())`) $, the beauty is $ 15 $, which is the maximum.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分