A1106. [COCI-2007_2008-contest1]#6 ZAPIS
编程题
省选/NOI-
知识点
题目描述
A regular bracket-sequence is a string of characters consisting only of opening and closing brackets, and satisfying the following conditions:
• An empty string is a regular bracket-sequence.
• If A is a regular bracket-sequence, then (A), [A] and {A} are also regular bracket-sequences.
• If A and B are regular bracket-sequences, then AB is also a regular bracket-sequence.
For example, the sequences [({})], [](){} i [{}]()[{}] are regular, but the sequences [({{([, []({)} and [{}])([{}] are not.
Ivica has found a string which looks like it could be a regular bracket-sequence. Some of the characters have become smudged and illegible, and could have been any character.
Write a program that calculates how many ways the illegible characters in the string can be replaced by brackets so that the result is a regular bracket-sequence. This number can be very large, so output only its last 5 digits.
• An empty string is a regular bracket-sequence.
• If A is a regular bracket-sequence, then (A), [A] and {A} are also regular bracket-sequences.
• If A and B are regular bracket-sequences, then AB is also a regular bracket-sequence.
For example, the sequences [({})], [](){} i [{}]()[{}] are regular, but the sequences [({{([, []({)} and [{}])([{}] are not.
Ivica has found a string which looks like it could be a regular bracket-sequence. Some of the characters have become smudged and illegible, and could have been any character.
Write a program that calculates how many ways the illegible characters in the string can be replaced by brackets so that the result is a regular bracket-sequence. This number can be very large, so output only its last 5 digits.
输入格式
The first line contains an even integer N (2 ≤ N ≤ 200), the length of the string.
The second line contains the string. Illegible characters are represented by the '?' character.
The second line contains the string. Illegible characters are represented by the '?' character.
输出格式
Output the number of regular bracket-sequences the string could have read.
输入输出样例
输入 #1
6 ()()()
输出 #1
1
输入 #2
10 (?([?)]?}?
输出 #2
3
输入 #3
16 ???[???????]????
输出 #3
92202
说明/提示
In the second example, the three matching regular bracket-sequences are ({([()])}), ()([()]{})
and ([([])]{}).
and ([([])]{}).