思路可以看这个链接：https://biaodigit.github.io/LeetCode/0012/#%E8%A7%A3%E9%A2%98%E6%80%9D%E8%B7%AF-%E8%B4%AA%E5%BF%83%E7%AE%97%E6%B3%95

#include<bits/stdc++.h>
using namespace std;

int arr[20]={1000,900,500,400,100,90,50,40,10,9,5,4,1};//13
string sl[20]={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};

int main(){
    int n;
    cin>>n;
    vector<string>ans;
    for(int i=0;i<13;i++){
        if(n<arr[i])continue;
        while(n>=arr[i]){
            n-=arr[i];
            ans.push_back(sl[i]);
        }


    }
    for(int i=0;i<ans.size();i++){
        cout<<ans[i];
    }


    return 0;
}