평균 구하기

#include <string>
#include <vector>

using namespace std;

double solution(vector<int> arr) 
{
    double answer = 0;
    double size = arr.size();
    int i;
    
    for(i = 0; i < (int)size; i++)
    {
        answer += (double)arr[i];
    }
    answer = answer / size;
    
    return answer;
}