프로그래머스 - 문자열 내 마음대로 정렬하기 (C++)

#include <iostream>
 
 
 
#include <string>
#include <vector>
#include <algorithm>
 
using namespace std;
 
int N;
 
bool compare(string a, string b){
    
    if(a[N] != b[N])
        return a[N] < b[N];
    else{
        return a < b;
    }
}
 
vector<string> solution(vector<string> strings, int n) {
 
    N = n;
 
    sort(strings.begin(), strings.end(), compare);
 
    return strings;
}
 
 
 
int main(void){
    ios_base :: sync_with_stdio(false); 
    cin.tie(NULL); 
    cout.tie(NULL);
    
    vector<string> strings{"abce", "abcd", "cdx"};
    int n = 2;
 
    vector<string> answer = solution(strings, n);
 
    for(int i = 0; i < answer.size(); i++){
        cout<<answer[i]<<" ";
    }
 
    return 0;
}