Determining if a string is balanced

Problem

Given a string containing only parentheses, write a function to determine if the string is balanced. A string is balanced if every open parenthesis has a corresponding close parenthesis and vice versa.
Example input: "()()"
Example output: True
Example input: "((()))"
Example output: True
Example input: "())("
Example output: False

Solution

This solution is in C++. Our A.I. can create solutions in multiple languages.

kayakane

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

using namespace std;

bool isBalanced(string s) {
	stack<char> st;
	for (int i = 0; i < s.length(); i++) {
		if (s[i] == '(') {
			st.push(s[i]);
		}
		else if (s[i] == ')') {
			if (st.empty()) {
				return false;
			}
			else {
				st.pop();
			}
		}
	}
	return st.empty();
}

int main() {
	string s1 = "()()";
	string s2 = "((()))";
	string s3 = "())(";
	cout << isBalanced(s1) << endl;
	cout << isBalanced(s2) << endl;
	cout << isBalanced(s3) << endl; return 0;
}