please implement one recursion that justifiably improves runtime

Problem 1: Stack and Queues Input: exp=66[0]{}{[00]0}9" Output: Balanced Explanation: all the brackets are well-formed Input: exp=6C[(])" Output: Not Balanced Explanation: 1 and 4 brackets are not balanced because there is a closing ' ] ' before the closing '(' The idea is to put all the opening brackets in the stack. Whenever you hit a closing bracket, search if the top of the stack is the opening bracket of the same nature. If this holds then pop the stack and continue the iteration, in the end if the stack is empty, it means all brackets are well-formed. Otherwise, they are not balanced. With the implementation below, please implement one recursion that justifiably improves runtime. else cout