Lecture 235:- Program for 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 works similarly to the previous one. It uses the isMatching function to check if two parentheses characters match each other. The isBalanced function uses a stack to check if the given expression has balanced parentheses. It 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.

The main function takes an expression as input and calls the isBalanced function to determine if the expression has balanced parentheses. The result is printed accordingly.