[프로그래머스 2] 쇠막대기 (C/C++) (★★)

#include <string>
#include <vector>
#include <stack>
using namespace std;
 
int solution(string arrangement) 
{
    stack<char> st;
    int answer = 0;
    
    for(int i = 0; i < arrangement.size(); i++)
    {
        if(arrangement[i] == '(')
        {
            st.push('(');
        }
        else
        {
            st.pop();
            
            if(arrangement[i-1] == '(')
            {
                answer += st.size();
            }
            else
            {
                answer++;
            }
        }
    }
    
    return answer;
}