Lecture 236:- Let's Code Parenthesis Matching

Below is a C++ implementation of the Parenthesis Matching program using a stack:

cppCopy code

#include <iostream> #include <stack> #include <string> bool isMatching(char open, char close) {    return (open == '(' && close == ')') ||           (open == '[' && close == ']') ||           (open == '{' && close == '}'); } bool isBalanced(const std::string& expression) {    std::stack<char> parenStack;    for (char c : expression) {        if (c == '(' || c == '[' || c == '{') {            parenStack.push(c);        } else if (c == ')' || c == ']' || c == '}') {            if (parenStack.empty() || !isMatching(parenStack.top(), c)) {                return false; // Not balanced            }            parenStack.pop();        }    }    return parenStack.empty(); } int main() {    std::string expression;    std::cout << "Enter an expression with parentheses: ";    std::cin >> expression;    if (isBalanced(expression)) {        std::cout << "The expression is balanced." << std::endl;    } else {        std::cout << "The expression is not balanced." << std::endl;    }    return 0; }

This program uses a stack to check if the given expression has balanced parentheses. The isMatching function checks if two parentheses characters match each other. The isBalanced function iterates through each character in the expression, pushes opening parentheses onto the stack, and pops them when a corresponding closing parenthesis is encountered. If the stack is empty at the end, the expression is balanced; otherwise, it is not balanced.

In the main function, the user is prompted to enter an expression with parentheses. The program then calls the isBalanced function to determine if the expression has balanced parentheses and prints the result accordingly.