example5_balanced_parentheses.cpp

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#include <iostream>
#include <stack>
#include <string>

bool areParenthesesBalanced(const std::string& expression) {
    std::stack<char> stack;

    for (char c : expression) {
        if (c == '(' || c == '[' || c == '{') {
            stack.push(c);
        } else if (c == ')' || c == ']' || c == '}') {
            if (stack.empty()) return false;
            
            char top = stack.top();
            stack.pop();

            if ((c == ')' && top != '(') ||
                (c == ']' && top != '[') ||
                (c == '}' && top != '{')) {
                return false;
            }
        }
    }

    return stack.empty();
}

int main() {
    std::string expr1 = "{[()]}";
    std::string expr2 = "([)]";
    std::string expr3 = "((";

    std::cout << expr1 << " is " << (areParenthesesBalanced(expr1) ? "balanced" : "not balanced") << std::endl;
    std::cout << expr2 << " is " << (areParenthesesBalanced(expr2) ? "balanced" : "not balanced") << std::endl;
    std::cout << expr3 << " is " << (areParenthesesBalanced(expr3) ? "balanced" : "not balanced") << std::endl;

    return 0;
}