class Solution {

 public:

     string intToRoman(int num) {

     //哈希表初始化；

         unordered_map<int,char>hash;

         string str_initial1="IXCM";

         string str_initial2="VLD";

         int index=;

         for(int i=;i<=;i*=){

             hash[i]=str_initial1[index];

             index++;

         }

         index=;

         for(int i=;i<=;i*=){

             hash[i]=str_initial2[index];

             index++;

         }

         //通过哈希表和取余数来进行倒序获取罗马字符

         string s,re;

         int temp=num;

         int cnt=;

         index=;

         while(temp>){

             int pop=temp%;

             temp=temp/;

             if(pop==){cnt*=;continue;}

             else if(pop==){

                 s[index++]=hash[cnt*];

                 s[index++]=hash[cnt];

             }else if(pop==){

                 s[index++]=hash[cnt*];

                 s[index++]=hash[cnt];

             }else{

                 int flag=;

                 if(pop>){

                     flag=;

                     pop=pop-;

                 }

                 for(int i=;i<pop;i++){

                     s[index++]=hash[cnt];

                 }

                 if(flag==){

                     s[index++]=hash[cnt*];

                 }

             }

             cnt=cnt*;

         }

         //cout<<index<<endl;

         for(int i=;i<index;i++){

             re[i]=s[index-i-];

         }

         return re;

     }

 };

class Solution {

public:

    string intToRoman(int num) {

        vector<int> val={,,,,,,,,,,,,};

        vector<string> rom={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};

        int i=;

        string re="";

        for(int i=;i<val.size();i++){

           while(num>=val[i]){

               re+=rom[i];

               num-=val[i];

           }

        }

        return re;

    }

};