프로그래머스 같은 숫자는 싫어 [c++]

#include <vector>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>


using namespace std;

vector<int> solution(vector<int> arr) 
{
    vector<int> answer;
    
    stack<int>s;
    
    s.push(arr[0]);
    
    for(int i=1;i<arr.size();i++)
    {
        if(!s.empty())
        {
            int temp = s.top();
        
            if(temp != arr[i])
                answer.push_back(temp);

            s.pop();
            s.push(arr[i]);
        }
             
    }
    
    answer.push_back(arr[arr.size()-1]);

    return answer;
}