2262: Brackets
| Result | TIME Limit | MEMORY Limit | Run Times | AC Times | JUDGE |
|---|---|---|---|---|---|
|
|
3s | 8192K | 208 | 68 | Standard |
We give the following inductive definition of a " regular brackets " sequence:
- the empty sequence is a regular brackets sequence,
- if s is a regular brackets sequence, then (s) and [s] are regular brackets sequences, and
- if a and b are regular brackets sequences, then ab is a regular brackets sequence.
- no other sequence is a regular brackets sequence
(), [], (()), ()[], ()[()]
while the following character sequences are not:
(, ], )(, ([)], ([(]
Given a brackets sequence of characters a1a2 . . . an, your goal is to find the length of the longest regular
brackets sequence that is a subsequence of s. That is, you wish to find the largest m such that for indices
i1, i2, . . . , im where 1 ≤ i1 < i2 < . . . < im ≤ n, ai1 ai2 . . . aim is a regular brackets sequence.
For example, given the initial sequence ([([]])], the longest regular brackets subsequence is [([])].
Input
The input test file will contain multiple test cases. Each input test case consists of a single line containing only the characters (, ), [, and ]; each input test will have length between 1 and 100, inclusive. The end-of-file is marked by a line containing the word " end " and should not be processed.Output
For each input case, the program should print the length of the longest possible regular brackets subsequence on a single line.Sample Input
((())) ()()() ([]]) )[)( ([][][) end
Sample Output
6 6 4 0 6
This problem is used for contest: 41
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