| 2022 SYSU School Contest |
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| Finished |
Starlight Glimmer has a bracket sequence $$$s$$$ of lenght $$$n$$$, which only contains character '(', ')' and '?'.
She also has a value sequence $$$v$$$ of lenght $$$n$$$ constructed by two integer constants $$$a,b$$$ that $$$v_i=ai+b$$$.
Define that the partition of a sequence is a pair sequence $$$(l_i,r_i)$$$ of length $$$m$$$ if it satisfies $$$l_1\le r_1 \lt l_2\le r_2 \lt \dots \lt l_{m-1}\le r_{m-1} \lt l_m\le r_m$$$ and any substring $$$(l_i,r_i)$$$ is a valid bracket sequence.
The substring $$$(l,r)$$$ of $$$s$$$ is a string removed first $$$l-1$$$ characters and last $$$n-r$$$ characters of $$$s$$$, and Starlight Glimmer believes it valid if:
According to the above, Starlight Glimmer defines the value of $$$s$$$ is $$$\max_{partition}\sum v_{r_i+1-l_i}$$$.
Now Starlight Glimmer should and find the maximal value of $$$s$$$ if she replace all '?' to '(' or ')' in a optimal way.
The first line contains a single integer $$$n\ (1\le n\le 5\times 10^5)$$$ - the length of $$$s$$$.
The second line contains a string $$$s$$$ of lenght $$$n$$$ - denoting the bracket sequence $$$s$$$.
The third line contains two integer $$$a,b\ (-10^6\le a,b\le 10^6)$$$ - denoting $$$v_i=ai+b$$$.
Print a single integer - the maximal value of $$$s$$$ after replacement.
10 (?)(??(?)? 1 2
14
For the testcase, $$$v=[3,4,5,6,7,8,9,10,11,12]$$$.
The result of a possible replacement is '(()()(()))', and Starlight Glimmer could choose $$$(2,3),(4,5),(6,9)$$$ as a partition, the value of it is $$$v_2+v_2+v_4=4+4+6=14$$$.
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