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
amit1_sharma:
20201002 10:45:29
How for input "{{{}" answer is 1 while it should be 2? 

adarshgaur:
20200805 10:59:02
With dp it will be solved in O(N^2) but using stack(or similar concept) it can be implemented in O(N) 

akash_arelli7:
20200723 06:47:35
If you know how to implement stack. Just go with it. Don't waste your time. 

jeets:
20200716 09:03:14
What if No. of braces are odd?


kumar_anubhav:
20200627 10:07:22
AC in one go!!


robosapien:
20200603 01:20:52
Dont forget about the output format.. :/ 

broken_forever:
20200524 08:17:14
Try to use DP not stack...it provide better insight of DP


majd211:
20200523 07:48:42
Beware of output format!! It gave me 2 wrong answers. 

Ayush Mahajan:
20200515 15:04:49
Simple greedy will work. 

pharoaheye:
20200515 10:22:39
very easy problem , just watch carefully on output format

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 