Integer to Roman

class Solution {
private:

static int a[200];
static map<int,string> mp;
static vector<int> vec_list;


void init (){
if(a['I'])return ;

a[0] = 0;
a['I'] = 1;
a['X'] = 10;
a['C'] = 100;
a['M'] = 1000;
a['V'] = 5;
a['L'] = 50;
a['D'] = 500;

char s[] = "IXCMVLD";

for(int j = 0 ; s[j] ; j ++)
{
vec_list.push_back(a[ s[j] ]);
mp[a[s[j]]] += s[j];
for(int i = 0 ; s[i] != 'M' ; i ++)
{

if(a[ s[i] ] < a[s[j]] )
{
int tmp = a[ s[j] ] - a[ s[i] ] ;
if(tmp == 49||tmp == 99||tmp == 490||tmp == 499||tmp == 990||tmp == 999)continue;
vec_list.push_back(tmp);
mp[ tmp ] += s[i];
mp[ tmp ] += s[j];
}
}
}
sort(vec_list.begin(),vec_list.end());

}

public:
string intToRoman(int num) {
init();
string n = "";

for(int i = vec_list.size() -1 ; i >= 0 ; i --)
{
while(vec_list[i]<=num){
num-=vec_list[i];
n += mp[vec_list[i]];
}
}

return n;
}
};
int Solution::a[200];
map<int,string> Solution::mp;
vector<int> Solution::vec_list;