Print Bracket Number

Print Bracket Number” is a stack based basic problem asked in technical round of product- based company. Here, in this problem, we are given a expression string of balanced brackets and our task is to print the bracket number when the expression is being parsed.


Expression: (())()
Bracket Number: 1 2 2 1 3 3
Expression: ()()()
Bracket Number: 1 1 2 2 3 3 
Expression: (())()(())()
Bracket Number: 1 2 2 1 3 3 4 5 5 4 6 6

METHOD 1: Stack Based Solution

The steps to find and print the bracket number are as follows:

  1. Create an empty integer stack.
  2. Create a vector to store the bracket number as result and initialize a local variable, say, count with 0.
  3. Scan the expression string.
  4. If the character is open bracket ‘(‘, then push count into stack and vector both. Then increment count with 1.
  5. If the character is closing bracket ‘)’, then push top of stack into vector and pop out the stack.
  6. After the string is completely scanned, print the vector as result, which stores all the bracket numbers.

C++ Program to Find and Print Bracket Number is as follows:

/* C++ Program to Find Bracket Number */
using namespace std;

/* Function to Print Bracket Number */
void printBracketNumber(string str)
    /* Create an Empty Stack and a vector*/
    stack<int> st;
    vector<int> vc;
    int count = 1; /* A counter to store current bracket number */
    for(int i = 0; i < str.length();i++)
            If the character is open bracket, then push the count 
            into both vector and stack and then increment count with one
        if(str[i] == '(')
                If the character is closing bracket, then push top of stack
                into vector and then pop out the stack
    /* Printing the Bracket Number */
    cout<<"The Bracket Number for Given Expression is:\n";
    for(int i = 0; i < vc.size(); i++)
    cout<<vc[i]<<" ";
int main()
    string str = "(())()(()())";
The Bracket Number for Given Expression is:
1 2 2 1 3 3 4 5 5 6 6 4

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