
ZOJ Problem Set  2704
Given a string consisting of brackets of two types find its longest substring that is a regular brackets sequence. Input There are mutiple cases in the input file. Each case contains a string containing only characters ‘(’ , ‘)’ , ‘[’ and ‘]’ . The length of the string does not exceed 100,000. There is an empty line after each case. Output Output the longest substring of the given string that is a regular brackets sequence. There should be am empty line after each case.Sample Input ([(][()]]() ([)] Sample Output [()] Source: Andrew Stankevich's Contest #10 