codeforces#P1264D1. Beautiful Bracket Sequence (easy version)
Beautiful Bracket Sequence (easy version)
Description
This is the easy version of this problem. The only difference is the limit of $n$ - the length of the input string. In this version, $1 \leq n \leq 2000$. The hard version of this challenge is not offered in the round for the second division.
Let's define a correct bracket sequence and its depth as follow:
- An empty string is a correct bracket sequence with depth $0$.
- If "s" is a correct bracket sequence with depth $d$ then "(s)" is a correct bracket sequence with depth $d + 1$.
- If "s" and "t" are both correct bracket sequences then their concatenation "st" is a correct bracket sequence with depth equal to the maximum depth of $s$ and $t$.
For a (not necessarily correct) bracket sequence $s$, we define its depth as the maximum depth of any correct bracket sequence induced by removing some characters from $s$ (possibly zero). For example: the bracket sequence $s = $"())(())" has depth $2$, because by removing the third character we obtain a correct bracket sequence "()(())" with depth $2$.
Given a string $a$ consists of only characters '(', ')' and '?'. Consider all (not necessarily correct) bracket sequences obtained by replacing all characters '?' in $a$ by either '(' or ')'. Calculate the sum of all the depths of all these bracket sequences. As this number can be large, find it modulo $998244353$.
Hacks in this problem in the first division can be done only if easy and hard versions of this problem was solved.
The only line contains a non-empty string consist of only '(', ')' and '?'. The length of the string is at most $2000$.
Print the answer modulo $998244353$ in a single line.
Input
The only line contains a non-empty string consist of only '(', ')' and '?'. The length of the string is at most $2000$.
Output
Print the answer modulo $998244353$ in a single line.
Samples
??
1
(?(?))
9
Note
In the first test case, we can obtain $4$ bracket sequences by replacing all characters '?' with either '(' or ')':
- "((". Its depth is $0$;
- "))". Its depth is $0$;
- ")(". Its depth is $0$;
- "()". Its depth is $1$.
So, the answer is $1 = 0 + 0 + 0 + 1$.
In the second test case, we can obtain $4$ bracket sequences by replacing all characters '?' with either '(' or ')':
- "(((())". Its depth is $2$;
- "()()))". Its depth is $2$;
- "((()))". Its depth is $3$;
- "()(())". Its depth is $2$.
So, the answer is $9 = 2 + 2 + 3 + 2$.