ANARC09A  Seinfeld
I’m out of stories. For years I’ve been writing stories, some rather silly, just to make simple problems look difficult and complex problems look easy. But, alas, not for this one.
You’re given a non empty string made in its entirety from opening and closing braces. Your task is to find the minimum number of “operations” needed to make the string stable. The definition for being stable is as follows:
 An empty string is stable.
 If S is stable, then {S} is also stable.
 If S and T are both stable, then ST (the concatenation of the two) is also stable.
All of these strings are stable: {}, {}{}, and {{}{}}; But none of these: }{, {{}{, nor {}{.
The only operation allowed on the string is to replace an opening brace with a closing brace, or visaversa.
Input
Your program will be tested on one or more data sets. Each data set is described on a single line. The line is a nonempty string of opening and closing braces and nothing else. No string has more than 2000 braces. All sequences are of even length.
The last line of the input is made of one or more ’’ (minus signs.)
Output
For each test case, print the following line:
k. N
Where k is the test case number (starting at one,) and N is the minimum number of operations needed to convert the given string into a balanced one.
Example
Input: }{
{}{}{}
{{{}

Output: 1. 2
2. 0
3. 1
hide comments
insomniac:
20160217 23:09:38
no dp! no stack! O(n) time O(1) space :) 

parkjinsang:
20160211 14:47:14
How to solve this problem using dp? anyone? 

PRANJIT BHARALI:
20160204 20:11:01
lol.. !!! 

try2catch:
20160123 10:35:01
single shot AC problem....... B)


dwij28:
20160113 06:12:51
150th AC.. Horrible input format.. I got an AC without stack, but my stack solution failed for some unknown reasons.. Also, people who used DP to solve this are trying to cut nails with a sword. DP is so powerful, why waste it on adhoc stuff ? 

Akshay Damle:
20151016 18:04:15
Input format weird. Python: WA, C++: AC. Same logic. 

Shubham Garg:
20150928 13:03:54
There is definitely some problems in the input when used getchar () for taking input it costed me 4 wrong answers but using scanf got accepted. 

topke:
20150924 20:55:30
@arjun well you can do it with just one variable storing information or you can use stack it does not matter since you only store one type of brackets you just need size :D 

prakash_reddy:
20150914 20:33:36
easy one stack implementation :) take care of output format costed me 1 WA 

simarsher220:
20150830 22:08:13
Last edit: 20150831 17:00:48 
Added by:  Mohammad Kotb 
Date:  20091128 
Time limit:  3.236s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 BASH JSRHINO 
Resource:  http://www.icpcanarc.org 