Identify and mark unmatched parenthesis in an expression

Given an expression, find and mark matched and unmatched parenthesis in it. We need to replace all balanced opening parenthesis with 0, balanced closing parenthesis with 1 and all unbalanced with -1.

Examples:

Input : ((a) 
Output : -10a1

Input : (a))
Output : 0a1-1

Input  : (((abc))((d)))))
Output : 000abc1100d111-1-1



The idea is based on stack. We run a loop from the start of the string upto end and for every ‘(‘, we push it into stack. If stack is empty and we encounter an closing bracket ‘)’ the we replace -1 at that index of the strig. Else we replace all opening brackets ‘(‘ with 0 and closing brackets with 1. Then pop from the stack.

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// CPP program to mark balanced and unbalanced
// parenthesis.
#include <bits/stdc++.h>
using namespace std;
  
void identifyParenthesis(string a)
{
    stack<int> st;
  
    // run the loop upto end of the string
    for (int i = 0; i < a.length(); i++) {
  
        // if a[i] is opening bracket then push 
        // into stack
        if (a[i] == '(') 
            st.push(i);
          
        // if a[i] is closing bracket ')' 
        else if (a[i] == ')') {
  
            // If this closing bracket is unmatched
            if (st.empty()) 
                a.replace(i, 1, "-1");
              
            else {
  
                // replace all opening brackets with 0
                // and closing brackets with 1
                a.replace(i, 1, "1");
                a.replace(st.top(), 1, "0");
                st.pop();
            }
        }
    }
  
    // if stack is not empty then pop out all
    // elements from it and replace -1 at that
    // index of the string
    while (!st.empty()) {
        a.replace(st.top(), 1, "-1");
        st.pop();
    }
  
    // print final string
    cout << a << endl;
}
  
// Driver code
int main()
{
    string str = "(a))";
    identifyParenthesis(str);
    return 0;
}

chevron_right






                        filter_none









Java














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// Java program to mark balanced and  


// unbalanced parenthesis.  


import java.util.*; 


  


class GFG 


{ 


static void identifyParenthesis(StringBuffer a)  


{  


    Stack<Integer> st = new Stack<Integer>();  


  


    // run the loop upto end of the string  


    for (int i = 0; i < a.length(); i++) 


    {  


  


        // if a[i] is opening bracket then push  


        // into stack  


        if (a.charAt(i) == '(')  


            st.push(i);  


          


        // if a[i] is closing bracket ')'  


        else if (a.charAt(i) == ')')  


        {  


  


            // If this closing bracket is unmatched  


            if (st.empty())  


                a.replace(i, i + 1, "-1");  


              


            else 


            {  


  


                // replace all opening brackets with 0  


                // and closing brackets with 1  


                a.replace(i, i + 1, "1");  


                a.replace(st.peek(), st.peek() + 1, "0");  


                st.pop();  


            }  


        }  


    }  


  


    // if stack is not empty then pop out all  


    // elements from it and replace -1 at that  


    // index of the string  


    while (!st.empty()) 


    {  


        a.replace(st.peek(), 1, "-1");  


        st.pop();  


    }  


  


    // print final string  


    System.out.println(a); 


}  


  


// Driver code  


public static void main(String[] args)  


{ 


    StringBuffer str = new StringBuffer("(a))");  


    identifyParenthesis(str);  


} 


} 


  


// This code is contributed by Princi Singh 



















                        chevron_right







                        filter_none










Output:


0a1-1



          
          
          
          

            

    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts:
Image
smarakchopdar
Check out this Author's contributed articles.
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on  the "Improve Article" button below.


Improved By :  HARDY_123, princi singh


      
      
      
      

      

      
					
		

    Article Tags : 
Stack
Strings

           	
Practice Tags : 
Strings
Stack

        

         

         
 
         
        Be the First to upvote.

                

        



        
        
        
        
        

    

            

            1.7
            

            

             
                 Based on 10 vote(s)
                    

            
            
            
            
            
        

        
        

        

        

        

        

        

        


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.